PHOENIX -- Athletics third baseman Scott Sizemore will miss the entire 2012 season after tearing a ligament in his left knee last weekend during Oakland's first full-squad workout.
Sizemore was injured Saturday at Oakland's spring training camp in Phoenix. He had an MRI and the A's announced Monday that he had torn his anterior cruciate ligament.
"Broken heart right here. Safe to say I've cried more over baseball than anything in my life," tweeted Sizemore's wife, Brooke.
The 27-year-old Sizemore was acquired by Oakland last May in a trade with Detroit. He hit .249 with 11 home runs and 52 RBIs in 93 games with the A's.
"I really feel badly for Scott," A's manager Bob Melvin said. "He's worked extremely hard and was ready for a breakout season this year. We were counting on him to provide some much-needed power from the right side of the plate. Now his total focus has to be on a successful surgery and rehabilitation so he can return stronger than ever."
Because of swelling, Sizemore will be re-evaluated in two weeks to see when a date for surgery can be set.
The injury came almost a month before the A's open the major league season. They play Seattle on March 28 in Tokyo to start a two-game series.
Sizemore, who broke his left ankle in 2009 during Arizona Fall League play, was expected to be in the opening day lineup.
Donaldson played third base during his junior year at Auburn and was used at third 53 times in the Athletics' organization.
Melvin indicated that Rosales, Sogard and the Timmons would be more valuable as utility players. The A's have 10 infielders in camp.