ORCHARD PARK, N.Y. -- Pittsburgh Steelers rookie right guard David DeCastro may be out for an extended period of time after sustaining a potentially serious right knee injury early into Pittsburgh's 38-7 preseason win over the Buffalo Bills on Saturday night.
Coach Mike Tomlin said DeCastro's injury is "potentially severe," before adding that the team will know more about the injury after DeCastro has an MRI on the knee.
DeCastro was hurt while pass blocking as Pittsburgh faced third-and-8 at its 6-yard line on its second possession. DeCastro's right leg twisted beneath him after being bowled over by defensive tackle Marcell Dareus.
DeCastro, the 24th overall selection out of Stanford who started Saturday's game over Ramon Foster, lay in the end zone for a few minutes as trainers worked on his leg. He briefly got up on his own, but was unable to put any weight on his right leg. He took a few hops before trainers stopped him and called for a cart.
Tomlin was more optimistic about defensive end Brett Keisel, who hurt his left ankle late in the first quarter and didn't return.
"We held him out as a precaution," Tomlin said. "I think he's got a mild high ankle (sprain). He should be ready to go for us."
Pittsburgh's defensive line already is depleted with defensive tackle Casey Hampton sitting out his third preseason game while coming off right knee surgery. Hampton is practicing with the team after being activated off the physically-unable-to-perform list on Aug. 17.
Meanwhile, Tomlin didn't have any update on receiver Mike Wallace's status. Wallace has been in a contract holdout since the beginning of training camp.