Hideki Matsui says he will work on his knees this offseason in hopes that he'll be healthy enough to play in the field next year. Matsui, who will become a free agent this winter, knows that his chances of being re-signed by the Yankees will increase greatly if he is able to play left field again. He hasn't played in the outfield since June 2008. "That's going to be a challenge that I'm going to have to work on during the offseason," Matsui told the New York Daily News. "That's something that I'm going to be working on, trying to get back to the outfield and seeing how capable I'll be."