(Reuters) - Double world silver medallist Christian Coleman was keen to keep his name in the spotlight after a breakthrough campaign and the American sprinter ensured that was the case with an astonishing dash on Friday.

Athletics - Team USATF Press Conference - London, Britain - August 3, 2017 USA's Christian Coleman during the press conference REUTERS/John Sibley

The 21-year-old continued his meteoric rise to the upper echelons of global sprinting when he shattered a two-decade old 60 metres world record with a blazing time of 6.37 seconds at Clemson, South Carolina.

“Great start to my career,” tweeted Coleman, in his first full year as a professional athlete.

The time, if ratified by global governing body IAAF, shaves 0.02 seconds off the mark countryman Maurice Greene initially established in 1998 and then matched in 2001.

“I’m in disbelief,” Coleman’s coach Tim Hall told Reuters. “This was his season opener. It was totally unexpected.”

The two had chosen the small meeting at Clemson University to see where the talented sprinter stood in terms of upcoming competitions, including next month’s Boston Indoor Grand Prix and March’s world indoor championships in Birmingham, England.

“So we got through the prelims and felt pretty good since he backed off a little before the finish and still ran 6.47,” Hall said.

The time was the fastest in the world this year and 0.02 seconds slower than Coleman’s personal best.

“So we talked a little bit more before the final,” Hall said. “And like I always tell him, I said: ‘Relax, no pressing and allow the run to happen.’

“That was the result.”

Coleman’s tag as America’s next sprint hope was established last year when he clocked a world-best 9.82 seconds in the 100m at the U.S. collegiate championships before he edged the legendary Usain Bolt for silver at the world championships.

He went on to claim a second silver medal in London as the American quartet were edged out by hosts Great Britain in the 4x100m relay.

“We have been having some great practice sessions,” Hall said. “And he has been improving his strength development, so I guess it is all coming together.”

Ironically, after the race, Hall said Coleman told him the start had not felt right, which pleased the coach.

“Anytime I hear that from an athlete that means they are getting close to doing what we are trying to get accomplished,” Hall said.

“It might not have felt right to him, but it couldn’t have been wrong if he ran that fast.”

So how fast can the former Tennessee sprinter run?

“We will get back to Knoxville and look at the tape and see the technical things we can improve on to get even faster,” Hall added.

“Today was a pretty good starting point.”