Brett Anderson, scheduled to start on opening day for the Oakland Athletics, strained a muscle in his upper right back and left Sunday's 7-5 win over Arizona after facing just two batters.
Anderson indicated that the injury was nothing serious. The lefty said he came out as a precautionary measure.
After Adam Eaton led off with a single, former Oakland infielder Cliff Pennington hit a sharp grounder that caromed off the glove of third baseman Josh Donaldson.
Nobody was covering third base and Eaton took off. Anderson ran over to the bag but was too late to get Eaton.
Anderson kept twisting and rubbing his neck following the play. After consulting with manager Bob Melvin and the team's medical staff, Anderson exited.
Jed Lowrie homered and doubled for the A's.