Exactly 45 years ago today, Margaret Court, Australia's 30-year-old multiple Grand Slam winner, stepped onto a court in the tennis outpost of Ramona, California.
All she had to do was defeat the smaller, 55-year-old opponent in pebble specs at the other end, and a prize of $10,000 (£7,400/€8,400) was hers. The only complicating factor was that the figure on the opposite side of the net was a male - Bobby Riggs.
And Riggs was no mug. As a 21-year-old, despite his diminutive 5ft 7in frame, he had won the Wimbledon and US Open titles with a game based on guile and strategy rather than power. Thirty-four years down the line, however, he was a far from athletic figure, despite having devoted himself to his preparations for a challenge match that captured the public imagination.
While the match was couched in the rhetoric of the sex war, Riggs' motivation in issuing a challenge to three of the leading women players of the time - Court, and the US pair of Billie Jean King and Chris Evert - was essentially about money.
An inveterate gambler who boasted in his 1949 autobiography that he had made $105,000 (£78,000/€88,000) on backing himself to win the singles, doubles and mixed doubles at the 1939 Wimbledon Championships, Riggs was long retired, but an active member of the senior circuit.
It was a time of broad social change for women, and in tennis King was leading calls for parity with men in terms of prize money. Riggs, meanwhile, was demanding more prize money for ex-champions such as himself, while mocking King's own pay crusade.
Then Riggs, whose whole game was about spotting opportunities, spotted a big one. Claiming that the female game was inferior, and that the top women players could not beat him despite his age, he sent out his triple challenge via telegram.
Initially, no-one responded. King, whom he teasingly described as "the sex leader of the revolutionary pack" didn't want to know, seeing no benefit in such an enterprise for women's tennis.
Riggs, a masterful self-publicist, got to work on making it happen. As Selena Roberts noted in a 2005 New York Times article, his favourite t-shirt at that time bore the acronym WORMS - the World Organization for the Retention of Male Supremacy.
Riggs also had a goading collection of one-liners. Example: "Women who can do. Those who can't become feminists." Example: "Women belong in the bedroom and kitchen, in that order."
While Riggs' initial pursuit of King proved ineffective, he successfully courted Court. In contrast to King - who had rebelled against the male tennis establishment with eight other women players in 1970 and established the Virginia Slims tournament - this Australian wife and mother was conservative and, as of 1972, a committed Christian.
Although she entered into a little badinage with her male opponent, the potential socio-political reverberations of what became a very high profile challenge were largely lost on her.
Hard as it may be for the contemporary reader to believe, back in those days most companies regarded female workers as potential liabilities and maternity risks.
Riggs was clearly playing up his chauvinistic role. But King, and others, feared a victory over the leading female player of the day - Court finished 1973 as champion in three of the four Grand Slams - would be seen by many as an ugly form of confirmation, and cause for crowing, if not worse.
King later recalled Court telling her she was going to take up the Riggs challenge, adding that she would be collecting $10,000. Her perennial rival asked her to promise one thing - that she would win.
On the eve of the match, King told reporters: "Our reputation is at stake, and I'm afraid Bobby will win. Here is an old jerk who dyes his hair, waddles like a duck and has trouble seeing. We have nothing to gain."
As King later pointed out: "Margaret didn't see the bigger picture."
While Court appeared to be viewing the impending contest in terms of an exhibition match, her opponent, as Riggs' son Larry vouchsafed, was seriously engaged.
"For three or four months, we're talking running every day, playing six hours of tennis a day," Larry told Roberts.
"Train, train, train. He was playing the best tennis of his life."
Riggs also got himself hooked up with Rheo Blair, the Hollywood nutritional guru, and the papers were soon running stories of his diet of protein, dairy products and 415 vitamins a day under headlines such as "No Booze, No Broads, Vows Bobby".
In the 48 hours before the match the mind-games began as Riggs played up its significance to an opponent, who - despite her unmatched annexation of singles titles - had shown herself vulnerable to odd lapses against supposedly inferior opponents.
As a crowd of around 5,000 in temporary stands awaited the start, Riggs pulled another stroke as the two players met in front of Pat Summerall, commentating on the spectacle for CBS Sports.
"For the nicest mother in tennis," Riggs announced with a grin as he presented Court with a dozen roses. "Happy Mother's Day." She curtsied as she received them.
Court had reportedly been dealing in practice with the power of hitting partner Tony Trabert. But it soon became clear that this was a pointless approach.
From the start, the wily Riggs denied Court any pace with which to work, dinking over his serves, and mixing drop shots and lobs in the afternoon sun.
Court wobbled, and effectively collapsed, failing to make more than half of her first serves en-route to a 6-2, 6-1 defeat.
"Now I want King bad. I'll play her on clay, grass, wood, cement, marble or roller skates," Riggs declared. "We got to keep this sex thing going. I'm a woman specialist now."
King felt impelled to accept the challenge. Now there was indeed something to prove - or rather, to disprove…
And Riggs v Court turned out to have been a noisy prequel to the main event - Riggs v King. On September 20 of the same year, Riggs - whose victory had landed him on the cover of Sports Illustrated and Time - had his wish.
This time the venue was the Houston Astrodome, with an attendance of 30,472 people - which remains the largest audience to see a tennis match in the United States. The match, promoted as the "Battle of the Sexes", was televised in prime time on ABC with a best-of-five-sets, winner-takes-all prize of $100,000 (£74,000/€84,000).
King, then 29, had already won 10 Grand Slam singles titles, and would go on to collect two more. Nobody could have accused her of failing to give value for money on any level in the warm-up, where she fully matched the Riggs schtick.
King entered the court in the style of Cleopatra, on a feather-adorned litter carried by four bare-chested muscle men dressed in the style of ancient slaves. Riggs followed in a rickshaw drawn by scantily clad models. Riggs presented King with a giant Sugar Daddy lollipop, and she responded by giving him a squealing piglet as a symbol of his male chauvinism.
Riggs, who was reported to have placed numerous bets on the match, had been given $50,000 (£37,000/€42,000) to wear a yellow Sugar Daddy jacket during the match, which he did - although he removed it after three games.
So much for the pantomime. What followed was a true drama.
King, who also competed in the Virginia Slims in Houston earlier in the week, won in straight sets, 6-4, 6-3, 6-3. But it was not as clear as it looked from the scoreline.
In the first set King fell behind 3-2 when Riggs broke her serve. At this point, she said, she realised that she "had to win" and broke straight back. King had studied the way Riggs had played against Court and rather than playing her own habitual aggressive game she kept mostly to the baseline, making her elder opponent run from side to side to cover her shots.
In the end, Riggs, finding himself out-Riggsed, had to revert to an earnest serve-and-volley game. That didn't cut it either.
The match had an audience of an estimated 50 million in the US and 90 million worldwide.
Afterwards King received another challenge from another former world number one on the seniors tour, Pancho Segura. She turned it down. The great rebuttal had already been made.
"I thought it would set us back 50 years if I didn't win that match," King later said. "It would ruin the women's tour and affect all women's self-esteem."
Riggs ran his somewhat ragged idea once more up the flagpole in 1985 when he and Vitas Gerulaitis, who was a year off retiring from the main circuit but still in the world's top 20, took on the established doubles partnership of Martina Navratilova and Pam Shriver in the self-styled Battle of the Sexes: The Challenge! They lost 6-3, 6-2, 6-4.
Almost 20 years later, with a title that was a clear nod to the Riggs-King meeting, tennis produced The Battle of the Champions as Jimmy Connors and Martina Navratilova staged a best-of-three sets match with hybrid rules.
Tennis matches between established male and female champions were not new. In 1888 the Wimbledon men's champion Ernest Renshaw gave women's champion Lottie Dod a 30-0 start in each game and beat her - just - 2-6, 7-5, 7-5.
In 1922, multiple Grand Slam champions Bill Tilden and Suzanne Lenglen played a single set at St Coud, in Lenglen's native France. When asked later about the match, Lenglen replied: "Someone won 6-0, but I don't recall who it was."
In 1933, Helen Wills, who had won Wimbledon the previous year, defeated Phil Neer, an occasional mixed doubles partner who had reached number 20 in the US rankings, 6-3, 6-4.
But while the Battle of the Sexes matches, as Riggs v Court and Riggs v King have subsequently become known, were preceded and succeeded by similar male v female challenges on the tennis court, they have never been matched in terms of their impact and resonance. Because of the way the matches were set up, because of the political volatility of the times, these matches within the span of just over four months were unique.
On January 9, 2016, Kaillie Humphries - double Olympic champion in the two-woman bobsleigh - demonstrated King-type spirit as she became the first woman to drive an all-female team against men in a four-person World Cup race.
Although her team finished last, Humphries knew their entry would not be a contender due to the 300 pound weight difference between her team and the all-male opponents.
But, not unlke King, her focus was on the bigger picture - the purpose was to help get a four-woman bobsleigh division added to the Olympics.
The battle of the sexes continues more competitively, however, in a number of sports where the playing field for males and females is relatively level, even if on a theoretical basis.
Ultra racing cyclist Seana Hogan is one of the greatest competitors in the history of the sport - male or female. During her career, Hogan has set a number of world records in cycling and won countless transcontinental races.
English sailor Dame Ellen MacArthur is another winner in a traditionally male arena.
In 2005, MacArthur broke the world record for the fastest solo circumnavigation of the globe.
More than a century earlier, at the 1902 World Figure Skating Championships, Madge Syers became the first woman skater to compete against men after noticing that the rules did not actually stipulate the gender of prospective competitors.
The legal loophole may have been her finest manoeuvre, but there were plenty of others on the ice as she won the silver medal. Indeed, most observers were convinced that she had deserved the gold.
Reanne Evans, who won the women's world snooker title a record 10 times in succession between 2005 and 2014, made a breakthrough in 2009. After winning 61 consecutive women's games and defeating the then world champion John Higgins 4-3 at the Six Red World Championship, she became the first woman since her world champion predecessor Allison Fisher to play on the main snooker tour after she was offered a wild card for the 2010-2011 season.
She failed to win a match, suffering 18 successive defeats. In 2015 she lost with honour, 10-8, to the 1997 world champion Ken Doherty in the opening qualifying round of the World Snooker Championship. Last year she went one better, defeating Robin Hull 10-8 in the first round of qualifying.
But for all her magnificent record, and ability to mix it with some of the best male players, Evans' career winnings total to little more than £11,000 ($15,000/€12,500). King would surely wince.
Equestrian is surely the paramount example of a sport where women can, and do, compete on level terms with men.
The quadrennial Eventing World Championship, for instance, was last won in 2014 by Germany's Sandra Auffarth, riding Opgun Louvo, on whom she won individual bronze at the London 2012 Olympics behind respective gold and silver medallists Michael Jung of Germany and Sara Algotsson of Sweden.
There have been four previous female winners of a Championship that began in 1966 - British Royal Zara Phillips, on Toytown in 2006, and three other British riders in Virginia Leng in 1986, Lucinda Green in 1982 and Mary Gordon-Watson in 1970. Try telling any of those women they don't match up to the men.
In dressage, women have dominated at recent Olympics, where Anky van Grunsven won three successive Dutch titles between 2000 and 2008, after which the next two golds went to Britain's Charlotte Dujardin.
Riding Valegro, Dujardin currently holds the complete set of the available individual elite dressage titles; the individual Olympic freestyle, the world freestyle and Grand Prix Special, the World Cup individual dressage and European freestyle and the Grand Prix Special titles. Dujardin is the first, and to date only, rider to hold this complete set of titles at the same time.
In February 1969, Diane Crump became the first female jockey to compete in a thoroughbred race in the United States, finishing tenth on a 48-1 runner at the Hialeah Park Trace Track in Florida.
There have been steady advances since for women jockeys, but in November 2015 the greatest flourish so far in this particular arena was achieved by Michelle Payne, who began her day as only the fourth female jockey to ride in the Melbourne Cup in its 155-year history and ended it – aboard 100-1 shot Prince of Penzance - as the first female winner.
"You know what?" Payne said. "It's not all about strength, there is so much more involved, getting the horse to try for you, it's being patient."
Patience has been a necessary quality for countless sportswomen down the years.
Nearly half a century on, it is as clear now as it was then that the Riggs gigs were not, and could never be, the opportunity for female players to announce their parity with men in terms of performance.
But the corrective victory of King, at that moment in US sporting and social history, counted profoundly.
Gloria Steinem, the journalist and activist who became unofficial spokeswoman for the American feminist movement in the late sixties and early seventies, wrote of King’s success: "You felt this was a symbolic match that was going to be used against women and to humiliate them if Billie Jean lost.
"And for her to take that on, to put herself under that pressure, is the true meaning of heroism."