"There's a chance he could pinch-hit this weekend, maybe even tonight," Red Sox manager Bobby Valentine said of Middlebrooks, who's fighting left hamstring tightness. "He's taking batting practice as we speak. I'll go and check him out."
Middlebrooks did some running on Thursday and Friday.
"Will was out yesterday; he ran about 70 percent," Valentine said. "He felt just OK. He ran today. He felt closer to 100 percent, so that's where he is. He's close."
The All-Star break starts on Monday.
"I hope to be back at some point in this series," Middlebrooks said. "That might be pushing it a little bit. We're not sure. We're just trying to keep getting it better and looking to be healthy for the long run."
With Middlebrooks out, Mauro Gomez made the start at third base on Friday for the second time in as many games. Nick Punto played second in place of Dustin Pedroia, who was placed on the disabled list prior to the game.