Jamaica's Asafa Powell and American Tyson Gay stayed on course for an epic 100 metres showdown by cruising through Saturday's heats at the World Championships.

World record holder Powell exploded from the blocks and slowed dramatically before the finish but his time of 10.01 seconds was still the quickest of the evening's quarter-final heats.

''It was as expected, nothing else,'' Powell told reporters.

''Everything is going according to my plan.'' Gay adopted similar tactics in winning his heat in 10.06 following a false start from lane six after both he and Powell had run conservatively during the morning session in Osaka.

''The false start kind of threw me off but that's the way it goes,'' Gay told reporters. ''I had to refocus. I think he shot the gun a little quick.

''The speed is there. I just need to execute my start and I'll be ready for tomorrow.'' The American sprint king had stuck to his assessment that Powell's world record of 9.77 could fall in tomorrow's final when they are scheduled to clash for the first time this year.

''I tried to run 10.3 but the track wouldn't allow me to do it,'' said Gay, who ran this season's fastest time of 9.84 at the US championships.

''It's the fastest track I've ever been on. I just couldn't really run slow -- it was kind of hard!'' Powell was less demonstrative but gave Osaka's super-fast track another thumbs-up after edging out Derrick Atkins of the Bahamas on a balmy evening in the western Japanese city.

Neither of the two red-hot favourites for gold has won a world title, Powell missing the 2005 championships in Helsinki through injury and Gay finishing fourth in the 200 metres.

Kim Collins of St Kitts and Nevis, the 2003 world champion, scraped into the semi-finals with the slowest qualifying time of 10.30.