Olympic and world champion Justin Gatlin clocked 9.88 seconds to outperform joint world record holder Asafa Powell in separate 100 metres races at the Prefontaine Classic in Oregon on Sunday.

Gatlin used his powerful acceleration from about 40 metres to win the first race convincingly before Powell took the second in a wind-assisted 9.93 seconds.

Gatlin matched Powell's world record of 9.77 seconds on May 12.

"It proves I am here to protect my house," American Gatlin said.

"I am a patriot of America and I came here to put on a great show and that's what I did."

Cool weather and rain had threatened to slow the two sprinters.

"I stumbled the first couple of steps, but it wasn't as swift as it could be," Gatlin said.

"I had two fast starters on my side (Michael) Frater and Leonard (Scott). Me and Leonard bumped arms three times during the race, so it got a little ugly but I made it through and prevailed."

Scott was second in 10.16 seconds and Jamaican world silver medallist Frater third in 10.17.

Powell slowed over the closing stages of his race but played down injury fears.

"It was a little bit cold and I got a little scared," said the Jamaican, who missed last year's world championships with a groin injury. "There was no pressure on me in the race so I just took it easy."

Powell said Gatlin's faster time meant nothing.

"It did not prove any point," he said after defeating Olympic 200 metres champion Shawn Crawford.

Powell and Gatlin shook hands after Powell's race and both said they were looking forward to racing head-to-head, though a proposed June 11 meeting in Gateshead, England, has been cancelled.