Hamm, who had proved nine days ago that he was healthy enough to compete at the Summer Games, resigned from the team. The men's gymnastics competition begins on Aug. 9, one day after the opening ceremony, and one of the team's three alternates will take Hamm's spot on the six-member squad.

"I have put my heart and soul into my comeback and done everything I could to get ready in time to compete in Beijing," said Hamm, in a statement sent by USA Gymnastics. "After returning home from the preparation camp, I had a few physical setbacks, and it became clear to me that my physical preparations would not be sufficient to properly represent the United States and contribute to the teams efforts to win a medal."

Hamm said he recently strained his rotator cuff and has been unable to perform all of his skills.

One of the three alternates -- Alexander Artemev, Raj Bhavsar and David Durante -- will now become an Olympic team member, pending decision by the men's gymnastics selection committee.

"Two weeks ago, he was great, he was awesome and did everything he needed to do to be at the Olympics," said Hamm's coach, Miles Avery, in a telephone call. "But I was saying all along that he needed to rest. But he pushed it."

Hamm, who will discuss his decision on a teleconference at 1 p.m. Eastern, performed all six events at a training camp in Colorado Springs two weeks ago. And on July 19, the selection committee said he had done enough to prove he could perform at the Olympic Games, despite his injury.

Hamm broke the fourth metacarpal in his right hand in May at the United States championships. He subsequently had surgery, where a doctor inserted a plate and nine screws to hasten the healing. At that training camp, Hamm said he felt 90 percent healthy, even going as far as to warn the Chinese gymnast Yang Wei -- a favorite to win the all-around in Beijing -- that he was going to provide stiff competition.

"They should be a little worried," Hamm said on July 19, of the Chinese. "I guess also Yang Wei should be a little worried, too. He's probably counting on me being out."

Hamm's absence from the team leaves the team without its leader and the man who had led the Americans to silver medal in the team competition four years ago in Athens.

"We admire Paul for making this difficult decision," said Steve Penny, president of USA Gymnastics, in a statement. "Paul's comeback this year has been phenomenal, made even more impressive following the injury to his hand. He has raised the level of determination among the entire team to put forth a medal winning effort in China."