OAKLAND, Calif. — Will Middlebrooks is not in the lineup Monday and is expected to be out for at least a few days with a strained left hamstring.
The question is whether the Red Sox will put him on the disabled list. Middlebrooks was injured when he stole second base in Seattle Sunday.
"He feels better today than he did yesterday and better than he expected to be today," manager Bobby Valentine said. "That's the only news we have and that's good. It's not discolored and that's good. But it's going to be some days. Maybe DL; maybe a few days. It's just one of those injuries."
The Red Sox already were operating with a three-man bench and an extra reliever. With Nick Punto at third base Monday night, the only reserves are Brent Lillibridge and Kelly Shoppach.
"We'll see how we go through tonight," Valentine said. "I wouldn't be surprised if we have someone here tomorrow."
The only infielders on the 40-man roster not in the majors are first baseman Mauro Gomez and shortstop Jose Iglesias. Valentine said he did not like the idea of using Mike Aviles at third base.
Monday night will be approximately the 30th game the Red Sox have played with a short roster because of an injured player not on the disabled list.
Middlebrooks joins Dustin Pedroia, Kevin Youkilis, Cody Ross, Ryan Sweeney, and others who had injuries that took a few days to figure out.
• Nothing official, but Sweeney expects to play a rehab game Thursday. "It's not 100 percent but I can run and hit and I need to see how I cut on it," said the outfielder, who is on the DL with a fracture in his left big toe.
• Scott Podsednik is playing for Pawtucket Monday night.
• Aviles, who was knocked out of the lineup by a case of the flu Sunday, is back and and feeling much better. "Everything hurt yesterday, even my teeth," he said.