The New York Mets placed starting shortstop Kaz Matsui on the 15-day disabled list Monday with a severely bruised left knee. The move is retroactive to June 17. Matsui, who recently had an MRI, injured the knee on the final play of last Thursday's win over Oakland after catcher Jason Kendall hit him as he tried to break up a double play. Matsui completed the play and recorded the game-ending double play, but stayed on the ground for several minutes before eventually being helped off the field. There is no timetable for Matsui's return, but general manager Omar Minaya did say the injury was serious. On the season, the second-year pro out of Japan is hitting just .234 with three homers and 21 RBI. The Mets are now without three second baseman as Miguel Cairo and Jeff Keppinger have both already been put on the DL. New York is now left with Chris Woodward and Marlon Anderson, the team's primary pinch-hitter, as its only second basemen. In other team-related news, reliever Dae-Sung Koo was activated from the disabled list, right-handed reliever Mike DeJean was released and outfielder Gerald Williams was recalled from Triple-A Norfolk. DeJean, a nine-year veteran, was 3-1 with a 6.31 ERA this year.