A lower-back strain has landed Kevin Youkilis on the disabled list. The Red Sox promoted Will Middlebrooks from Triple-A Pawtucket prior to Wednesday night's game to take the third baseman's roster spot. Middlebrooks, who was hitting .333 with a team-leading nine homers and 27 RBIs for the PawSox, was in Wednesday night's lineup against Oakland, batting eighth and playing third base.