Eugene, United States 

Olympic champion Marcell Jacobs withdrew from the 100m semi-finals at the World Athletics Championships due to a thigh injury, the Italian Athletics Federation (FIDAL) confirmed on Saturday.

Italian team doctor Andrea Billi said in a statement released just hours before Jacobs was due to race that the sprinter would not compete after being diagnosed with tightness in his right thigh.

Evaluation of the contraction had found a "clinical picture that can put muscle integrity at risk and lead to injury", Billi said.

Jacobs tweeted that it had been a "painful choice, I am forced to stop".

"I am a fighter and this is why I decided to be in Eugene," he said.

"Now, in order not to compromise the rest of the season by risking a more serious inury, I have to postpone the challenge.

"I promise I will do my best to make you dream!"

Jacobs' withdrawal marks another disappointment in a season disrupted by injury.

The 27-year-old pulled off one of the shocks of the Tokyo Olympics last year after storming to victory in the 100m in a time of 9.80secs.

However he did not race again in 2021 after that high point.

Jacobs kicked off this season with world 60m indoor gold in Belgrade in March, but intestinal problems saw him forced him to withdraw from a meet in Nairobi at the beginning of May.

That was compounded by a thigh injury in mid-May that disrupted his outdoor campaign and led him to withdrawing at short notice from several other meets.

On Friday, he qualified for the semi-finals after clocking 10.04sec in his opening heat, far from the European record of 9.80sec he set when winning the Olympic title in Tokyo last year.

The Italian looked to be moving gingerly as he raced at Hayward Field on Friday and later admitted he had struggled.

"I am not at my 100%," Jacobs said.

"Running 10.04 at half capacity of what I can run, I can say my physical shape is fine. I just need to get my legs ready," he said.

In his absence, favourites for the race include the strong US quartet of in-form Fred Kerley, who ran a sensational heat-winning 9.79sec, Marvin Bracey, Trayvon Bromell and defending champion Christian Coleman, who missed the Tokyo Olympics after missing three doping tests.

Other contenders include Jamaicans Oblique Seville and Yohan Blake, the 2011 world champion, and Canada's Olympic 200m gold medallist and two-time bronze medallist Andre de Grasse.

Botswana teenage sensation Letsile Tebogo, Japan's Abdul Hakim Sani Brown and Kenya's Ferdinand Omanyala, who only just managed to secure a last-minute visa to travel to the United States, could be in the running for a spot in the eight-man final.