OAKLAND, Calif. -- The disabled list remains a possibility for injured Red Sox third baseman Will Middlebrooks.

The rookie slugger’s tight left hamstring is progressing, but the team was no closer to making a decision on Tuesday.

“He’s coming along,” Red Sox manager Bobby Valentine said. “He’s a little better today than he was yesterday. That’s progress.”

Middlebrooks left Sunday’s game against the Seattle Mariners in the ninth inning with hamstring tightness after stealing second base. He’s out of the lineup for the second straight night Tuesday.

“We have the DL sitting there,” Valentine said. “We can backdate it any time we want if we feel like there’s not enough progress being made. He was able to touch his toes yesterday without any spasm or grabbing and that’s one of those hamstring tell-tale signs.”

Mauro Gomez, who was called up Tuesday with Daisuke Matsuzaka placed on the disabled list, is primarily a first baseman but originally was signed as a third baseman and could see time there. Nick Punto started at third Tuesday for the second straight game.

ROTATION SET: The Red Sox pitching rotation for the rest of the week is set, including the four-game series against the New York Yankees that will lead into the All Star break.

Aaron Cook will start Wednesday’s series finale against the Oakland Athletics. Franklin Morales had been the listed starter for that game, but Valentine said that was a typo and Cook has been the scheduled starter all along, with Morales slated to be available in relief Tuesday and Wednesday. Morales' last start was Thursday in Seattle.

For the Yankees series, Josh Beckett will start Friday. Morales and Felix Doubront will pitch Saturday’s doubleheader, and Jon Lester will go Sunday to close out the first half.