The forward picked up an injury in Tuesday's semifinal match against Japan that saw him come off the pitch after the end of the first half.
Giovani dos Santos has officially been ruled out of contention for Saturday's gold medal match against the Selecao, after it was determined that the muscle injury he sustained on Tuesday would not heal in time.
With three goals and three assists in the tournament, the Tottenham player had turned in one of the best performances for any player in the Olympic campaign and appeared at key times for Mexico along the way.
Dos Santos missed practice on Thursday in London and a member of El Tri's medical team told press that the full results from his tests would be released later that afternoon.
However, it was apparently leaked to the press that the prognosis was negative.
"It's a shame because Dos Santos had been giving the team so much," said wing back Miguel Ponce, one of the early candidates to replace Giovani in the starting lineup. "It's sad, but in the end if he's not there we'll play for him and for the country."
In the first half of Tuesday's semifinal match against Japan, Dos Santos suffered a muscle tear in his right leg that the player himself noted was serious enough to have him exit the game after the first half.
"I'm very sad. I'm out of the final due to a muscle tear, now I just have to recover and support my teammates this Saturday," Dos Santos wrote on his Twitter account after being told of the extent of his injury.
Mexico and Brazil will meet at Wembley on Saturday. The winner will take home its first gold medal in men's football.
Follow ERIC GOMEZ on