Youkilis is sidelined with a sprained left ankle and unlikely to play again in the WBC, manager Davey Johnson said Wednesday. Team USA's cleanup hitter and first baseman returned to Boston Red Sox camp in Fort Myers for an MRI.
Earlier injuries knocked infielders Dustin Pedroia and Chipper Jones and reliever Matt Lindstrom out of the tournament. Outfielder Ryan Braun is sidelined with a sore right side, but he's expected to be available when Team USA plays in the semifinals this weekend in Los Angeles.
The Americans advanced with a three-run rally in the ninth inning Tuesday night to eliminate Puerto Rico 6-5.