Eamon Sullivan has shocked the swimming world by breaking the 50m freestyle world record in a stunning performance at the NSW Open titles.

Sullivan said last week he wanted to be considered the "silent assassin" at this year's Beijing Olympics but his cover was well and truly blown by his brilliant one-lap dash this evening.

The time of 21.56 seconds shaved 0.08 of a second off sprinting great Alex Popov's mark of 21.64 set back in 2000.

Sullivan hacked almost half a second off his personal best time - a massive jump in such a frenetic event.

The laid-back West Australian was amazed by the performance, which shoots him straight into gold medal favouritism in Beijing.

"I just surprised myself," he said.

"Felt really, really good in the warm-up and working towards getting under 22 for the first time.

"I really don't know (how that happened).

"We have made some big gains in the gym and I knew if I put bits of my best race together we would be in for a shot at the 22. To take that much off my PB is amazing."

Sullivan initially thought he had stopped the clock at 22.56.

"Then I saw the line and was in shock," he said.

Head coach Alan Thompson paid tribute to Sullivan.

"That was great, to break a world record of one of the legends of the sport and a long-term world record," he said.

Having made the 2004 Athens Olympics, the 22-year-old Sullivan struggled to shake off a number of injuries before his breakthrough meet at the national championships 14 months ago.

He captured the 50m national record at that meet in Brisbane before reinforcing his growing status as a quality sprinter by collecting bronze at last year's world championships in Melbourne in the 100m and fifth in the 50m.

But for all the expectation surrounding him, precious few could have expected Sunday night's effort.

His coach this week praised him as being a very level-headed competitor and within minutes Sullivan was resetting his mindset before next month's Olympic trials.

"It will be good for me to have another outlook where people are worried about me," Sullivan said.

"It will be interesting I will have to have a chat with a lot of people and work out my game plan because instead of me targeting people, other people will be targeting me."

The pace will only enhance Sullivan's chances of collecting Australia's first Olympic gold medal in the 100m in 40 years after he produced a sizzling time of 48.28s on Friday night.

The 50m event was only introduced into the Olympic program in 1988 and Australia is yet have a title holder in the event.

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