American Fred Kerley led a US cleansweep as he stormed to victory in the men's 100m at the World Championships in Oregon on Saturday.

Kerley, in lane four, was down on Marvin Bracy for 95 metres of the tight race, but managed to outdip his teammate for victory in 9.86 seconds at Eugene's Hayward Field.

Bracy took silver in 9.88sec, Trayvon Bromell claiming bronze in the same time for a third-ever 100m world championship cleansweep for the United States after 1983 and 1991.

The fourth of the strong US quartet, Christian Coleman, the reigning world champion from Doha in 2019 who was banned from the Tokyo Olympics for missing three doping tests, finished sixth (10.01) despite an electric start.

"We said we were going to do it and we did! USA, baby!" Olympic silver medallist Kerley said to roars of approval and applause from a partisan home crowd.

It was far from plain sailing for the in-form Kerley, who set out his stall with a heat-winning 9.79sec on Friday, as all the sprinters got off to a good start.

Bracy and Coleman looked like they might deprive Kerley of a gold many had predicted he would win.

But they hadn't counted on his savage finishing skills, the former 400m runner showing all his strength at the line. Bromell also left it late to sneak onto the podium from lane eight.

As the crowd realised it was a US cleansweep, chants of "U-S-A" rang out and flags brandished.

Jamaica's Oblique Seville finished fourth in 9.97sec, just ahead of South African Akani Simbine, who was clocked at 10.01 like Coleman in sixth.

Japan's Abdul Hakim Sani Brown and Canada's Aaron Brown were seventh and eighth, in 10.06 and 10.07sec respectively.

Failing to advance from the semi-finals to the final were Canada's Olympic 200m champion Andre de Grasse, also a two-time 100m bronze medallist, and 2011 world champion Yohan Blake of Jamaica.

The build-up to the final was rocked by the decision of Olympic champion Marcell Jacobs to withdraw just hours before the semi-finals with a tightness in his right thigh.

Italian team doctor Andrea Billi said that evaluation of the contraction had found a "clinical picture that can put muscle integrity at risk and lead to injury".

Jacobs, who pulled off one of the shocks of the Tokyo Olympics last year after storming to victory in the 100m in a time of 9.80sec, was crowned world indoor 60m champion in Belgrade in March but has struggled with injury since.

"I am a fighter and this is why I decided to be in Eugene," he tweeted, saying it had been a "painful choice, I am forced to stop".