The A's reinstated Hiro Nakajima from the 15-day disabled list Thursday and optioned the rookie shortstop to Triple-A Sacramento.
A strained left hamstring sent Nakajima to the DL prior to Opening Day after it was expected he could compete for the starting shortstop job. He has been rehabbing with Sacramento since May 3 and has hit .265 with five RBIs during that time.
The A's signed Nakajima to a two-year contract in the offseason after he left Japan to play for Oakland.
Nakajima batted .311 with 13 homers in 136 games last season for the Seibu Lions.