SAN JUAN, Puerto Rico -- Two days after saying he expected to miss the rest of the Tournament of the Americas, Tracy McGrady was back in the starting lineup for the United States in its 91-65 win over Puerto Rico on Thursday night.

McGrady forgot to take his warmup jersey off as he went out for the opening tip and missed his first shot -- a wide-open 3-pointer -- before making his second to give the U.S. team an early 8-2 lead.

The win keeps the Americans undefeated at 8-0 through the first two rounds of the tournament.

The same two teams will play again Saturday night in the semifinals, with a berth in the Athens Olympics at stake.

The loser will get another chance at qualifying for Athens on Sunday in the third-place game against either Canada or Argentina.

Tim Duncan led the U.S. team with 16 points.

The U.S. team has already locked up the No. 1 seed in the medal round, and its coaching staff was watching intently from the fourth row of the stands as Argentina defeated the Dominican Republic 102-72 in Thursday night's first game.

McGrady was the U.S. team's leading scorer through the first four games, averaging 14.5 points, but he aggravated a sprained back against the U.S. Virgin Islands in the first round.

"If I continue to play it's going to make matters worse. So I'm just going to sit out the rest of the tournament unless something really happens (where I'm needed)," McGrady said Tuesday.

The U.S. team had continued to list him as day-to-day, and his return Thursday night was a game-time decision.