MIAMI -- When it seemed as though the injury news could not get any worse for Team USA, manager Davey Johnson announced on Wednesday that Kevin Youkilis has left the team because of a sore left ankle.
Youkilis returned to Fort Myers, where he was examined by the Boston Red Sox medical staff and underwent an MRI.
"Kevin Youkilis returned to Fort Myers, FL this afternoon to be examined by the Red Sox medical staff. He was diagnosed with a mild left ankle sprain as well as mild Achilles tendinitis in his left foot. Both MRI results were negative," the Red Sox said in a team release. "To limit movement and allow his ankle to heal, Youkilis will wear a walking boot for the next several days but is not expected to miss significant time."
Johnson said the injury happened three or four days ago, and that Johnson noticed Youkilis was in pain during Team USA's 6-5 comeback win over Puerto Rico.
Teammate Brad Ziegler said Youkilis was in such pain that after the game he could barely walk through the training room.
"He wasn't going to miss last night's game for the world," Johnson said. "We've been devastated by some key injuries."
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.
Johnson operated Wednesday's game with one position player on his bench.
Rules for replacing players leave the Americans hard-pressed to come up with a substitute for Youkilis, Johnson said.
"These things need to be addressed" in the future by WBC officials, Johnson said. "You just can't have this becoming a circus, playing guys out of position."
Adam Dunn played first base, despite the Washington Nationals not wanting their new offseason outfielder to move to the infield. Mark DeRosa would have been a candidate, but the Cleveland Indians told Johnson they did not want him playing first base.
Dunn said Johnson asked him after Tuesday night's game if he would play first, and since Dunn was signed as an outfielder/first baseman with the Nats, he figured it wouldn't be an issue.
"I don't even know where I'm playing with the Nationals," Dunn said. "It's true, I really don't."
He added he had packed his first-base glove with him, and then quipped his defensive skills are on par with Omar Vizquel.
"That's the only player I can compare my hands to," Dunn joked.
Amy K. Nelson is a staff writer for ESPN.com. Information from The Associated Press was used in this report.