In breaking the 31-year-old mark of 23.12m set by fellow American Randy Barnes, the 28-year-old Rio 2016 champion appeared to be completing a process that has been building steadily in recent seasons.

After having to accept world silver for a stupendous effort of 22.90m in Doha two years ago -where fellow American Joe Kovacs out-threw him by a centimetre in what was regarded as the greatest shot-put event ever – Rouser has consistently established himself as the main man in the event.

In 2020 he threw 22.60m indoors, just six centimetres shy of Barnes’s 1989 world mark, and then set an outdoor personal best of 22.91, joining Kovacs at number three in the all-time list.

In his first competition this year he set a world indoor record of 22.82m and at the arena in Eugene, Oregon that has been re-imagined and reconstructed ahead of staging the delayed World Athletics Championships next year he produced his epic effort in the fourth round of a competition where Kovacs eventually finished a distant second on 22.34m.

"It's a really special moment for me on my first time at the new Hayward Field," said Crouser, who had indicated his potent form by recording 22.92m in the morning’s qualification round - the fifth best throw in history and the second-best mark of his career.

"I've wanted that world record for so long, it feels like a weight has been lifted.

"I knew the strength and the power was there, I just had to get it into the ball.

"I've been thinking about this moment since I started throwing.

"To finally do it is pretty special."

Crouser had taken a first-round lead in the final with 22.61m, following it with 22.55m and 22.73m.

As soon as he launched the shot, and before it had landed well beyond the 23-metre line, Crouser punched the air with both fists, knowing he had released a huge throw.

Moments later the confirmation came on the scoreboard.

Crouser sent his fifth effort out to near the 23-metre line but it was ruled out as a foul, and he ended his series with 22.62m, his seventh throw of the day beyond 22 metres.

Barnes, the Atlanta 1996 Olympic gold medallist, had set his record at San Jose in May 1990, breaking the 1988 mark of 23.06m by East Germany's Ulf Timmermann.

In August 1990, Barnes was banned from competing for 27 months after testing positive for the anabolic steroid methyltestosterone at a competition in Malmö in Sweden.

In the only other final on the opening day of the trials, the men's 10,000 metres, Woody Kincaid produced a 53-second final lap to win in 27min 53.62sec.

Grant Fisher was second in 27:54.29 and Joe Klecker third in 27:54.90, with all three laying claim to Tokyo 2020 places having already beaten the qualifying mark of 27:28.00.

For Ben True, sixth at the 2012 Olympic trials and fifth in 2016, there was further frustration as he finished fourth in 27:58.88.

The opening day’s competition took place amidst swirling controversy over the scheduled appearance at the trials of the US 1500 and 5,000 metres record holder Shelby Houlihan despite her recent four-year ban after testing positive for the banned steroid nandrolone.

Houlihan, who insists her positive test came from eating a burrito with contaminated pork in it 10 hours earlier, failed in her appeal to the Court of Arbitration (CAS) for Sport, but was initially entered for the trials, with USA Track and Field (USATF) announcing: "Given there is an active appeal process, USATF will allow any athletes to continue competing until the process is completed."

But World Athletics issued a statement saying: "All Member Federations must respect CAS decisions under the world anti-doping code.

"We are talking to USATF."

The US Olympic and Paralympic Committee chief executive Sarah Hirshland later appeared to confirm a U-turn was imminent, saying: "The US Olympic and Paralympic Committee, together with USATF, can confirm that we will adhere to the WADA (World Anti-Doping Agency) Code and any CAS decisions that govern athlete participation in sanctioned events."

CAS is expected to release its full reasoning in the coming days, but Houlihan’s lawyer Paul Greene said an appeal to the Swiss Federal Tribunal was being considered.