A week after the Red Sox traded Kevin Youkilis, Red Sox third baseman Will Middlebrooks left Sunday's game in Seattle with hamstring tightness and the team is unsure of the severity of the injury.
"You don't really know with these things until the next day," Boston manager Bobby Valentine said after the game (via the Providence Journal).
Middlebrooks declined comment until he finds out more on Monday.
The rookie third baseman left the game after stealing second in the ninth inning of the 10-inning Red Sox victory. Middlebrooks walked in the ninth and finished 0 for 3, lowering his average to .298 on the season. He was replaced by Mike Aviles, who was a late scratch from the lineup because of illness.
The Red Sox currently have 13 pitchers, leaving only three men on the bench. Boston designated outfielder Darnell McDonald on Saturday to make room for Josh Beckett.