Middlebrooks left Tuesday's game against the Angels with right hamstring tightness, Pete Abraham of the Boston Globe reports. Although Middlebrooks managed to beat out an infield in the fourth inning, he hurt his hamstring in the process and was immediately lifted for a pinch runner. The Red Sox are labeling the injury "tightness" for now, but it would make sense if they sent him for additional testing. Brock Holt and Kelly Johnson seem like the top candidates to see opportunities at third base should Middlebrooks miss time, though Xander Bogaerts is an option as well.