Australia's Dylan Alcott has been crowned as the International Tennis Federation's quad world champion for the second consecutive year.
The honour was first awarded in 2017 when American David Wagner was the inaugural winner.
Melbourne-born Alcott opened his Grand Slam account for 2019 by claiming his fifth successive Australian Open quad singles title, defeating Wagner in the final on Rod Laver Arena.
It was a landmark year for the quad division of wheelchair tennis, with the introduction of quad singles and doubles events to the competition schedule at both the French Open and Wimbledon.
The 29-year-old Alcott made the most of this opportunity and triumphed on the clay of Paris and grass of London, only dropping one set during the two tournaments.
Victory over Wagner handed Alcott success in the quad final at Roland-Garros in June, while his doubles partner Andy Lapthorne of Great Britain was his victim in the decisive clash at Wimbledon.
But a surprise defeat to Lapthorne in the final of the US Open in New York City ended Alcott's dream of emulating his hero Rod Laver and winning a calendar-year Grand Slam.
That proved to be the only defeat Alcott suffered all year – in singles or doubles.
He posted a 16-1 win-loss record in singles and finished the year as world number one.
In doubles, Alcott was untouchable.
With three different partners, he secured the calendar-year Grand Slam which eluded him in singles.
It was sealed courtesy of his and Lapthorne’s defeat of American duo Wagner and Bryan Barten at the US Open.
In January, Alcott teamed up with fellow Australian Heath Davidson for victory at the Australian Open, while Wagner was his partner at Roland-Garros, and Lapthorne, at Wimbledon.
"It’s been a hugely exciting 2019, and becoming the first quad singles champion at both Roland-Garros and Wimbledon was a real thrill," Alcott said.
"While it was great to win the calendar Grand Slam in doubles, I was gutted to get so close to doing the same in singles, and missing out in the final in New York.
"But it just gives me more motivation for a big year in 2020."
Alcott's sights will be set firmly on Tokyo 2020 next year.
He already has four Paralympic medals, three of them gold, including one in wheelchair basketball at Beijing 2008 when at 17 he was the youngest member of the Australian Rollers team.
Alcott won the quad singles and doubles at Rio 2016 after switching sports to wheelchair tennis after earning a silver medal in wheelchair basketball at London 2012.
"I’m so grateful to all my team, my friends and family for their ongoing support, and really look forward to the challenges of another Paralympic year," Alcott said.