DETROIT (AP) - Tigers ace Justin Verlander underwent muscle repair surgery Thursday after injuring himself last month during offseason conditioning. Dr. Bill Meyers in Philadelphia performed the operation on Verlander, who is expected to need six weeks of rehab before being evaluated again. The first workout for Detroit's pitchers and catchers at spring training is scheduled for Feb. 14. The first spring training game is Feb. 25 against Florida Southern College. The team did not identify the "core muscle" that was repaired, but called the surgery successful. General manager Dave Dombrowski said he team expects Verlander to participate in spring training and "be in a position to compete" at the beginning of the 2014 season. Verlander went 13-12 last year with a 3.46 ERA for the AL Central champions.