"Even after Rashard Mendenhall's breakout performance last Sunday, the pecking order in the Steelers' backfield hasn't changed.

"Willie Parker's a proven commodity," offensive coordinator Bruce Arians said of the injured veteran who is still first on the depth chart at running back. "When Rashard is (proven), then we'll re-evaluate him. I hope it gets to that problem. I'd like to have those two healthy at the same time."

The Steelers are not there yet.

Parker did not practice Thursday because of turf toe. The injury has put his availability for Sunday's 1 p.m. game against the Detroit Lions in doubt, although Arians remains hopeful Parker will play.

Mendenhall rushed for 165 yards and two touchdowns while starting in place of Parker in the Steelers' 38-28 win over the San Diego Chargers. If Mendenhall plays well against the Lions, Arians said, "then, yes, you've got to look to re-evaluate the number of carries both guys get."

In addition to Parker, tight end David Johnson (ankle) didn't practice yesterday.

Strong safety Troy Polamalu (knee), guard Chris Kemoeatu (ankle) and linebacker Andre Frazier (shoulder) were limited in practice."