The Texas Rangers learned today that outfielder Nelson Cruz will miss about three weeks because of a strained left hamstring. Team physician Dr. Keith Meister made the prognosis after reviews the results of tests that Cruz underwent. To help the healing process, Meister gave Cruz an injection of platelet-rich plasma. The Rangers did not make a roster move with Cruz, but general manager Jon Daniels said he expects to put him on the disabled list before Tuesday's series opener against Tampa Bay. Outifelder Leonys Martin, the Cuban defector, would join the club from Triple-A Round Rock.