"I hit the bag hard," Choo said. "I don't know what happened but I wasn't comfortable and didn't want to make it worse."
Choo smacked a grounder that hit off pitcher Fernando Abad and caromed toward third baseman Josh Donaldson. Choo was originally called safe on a close play but the call was overturned after a challenge by Athletics manager Bob Melvin. It appeared that Choo landed awkwardly on the base while trying to beat the throw. Michael Choice took over in left field in the bottom of the inning.
Choo will likely get Tuesday and Wednesday off. The Rangers are off on Thursday so the best case scenario is likely to be Choo back in the lineup on Friday.
"We'll know tomorrow," manager Ron Washington said. "I just hope he comes back. We just have to wait and see what it shows tomorrow."
T.R. Sullivan is a reporter for MLB.com Read his blog, Postcards from Elysian Fields and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.