Vikings coach Brad Childress said Pro Bowl cornerback Antoine Winfield has a sprained right foot.

Winfield, who suffered the injury in the second quarter of a 33-31 victory against the Ravens, had an MRI on Monday morning. Childress said it's too early to tell whether Winfield will be able to play against the Steelers on Sunday. "People heal so differently it's hard to know," Childress said. "I would have thought [right tackle Phil] Loadholt's injury would have held him out longer than it held him out. Guys have different recuperative skills and I'm not going to rule him in or rule him out at this point." Childress also declined to speculate on how they would handle Winfield's absence if he can't play. Karl Paymah took over that spot Sunday, but they also could possibly move nickel back Benny Sapp to the outside and have rookie Asher Allen as the nickel. Allen has been inactive the first six games. "We have not even gone there yet," Childress said. "We just got done with the grades and talk about personnel in terms of who played what and how many plays did they have, how well did they do. So we haven't even started to address some of that. I thought Husain Abdullah came in there and gave us nine good snaps [at nickel] as well in there. So we've got different options." Childress was asked for his evaluation of Paymah, whot got beat on a 32-yard touchdown by Mark Clayton in the fourth quarter. "They made some plays on him," Childress said. "He was in position, in a couple instances I thought he got pushed off on on the very first one right on our sideline. But it's the same thing just like you can call holding every time we're probably going to tell him don't get pushed off on. Even though I'm going to tell the referee the guy can't push off. You go back and look at the TV copy it appears that way. The guy kind of held him by, kind of sat him down with a hand on his back but [Derrick] Mason's a good receiver and he's got all the craftiness of a good receiver." The Vikings pass defense continues to be a problem. Joe Flacco threw for 196 yards and two touchdowns in the fourth quarter alone. The Vikings now rank 24th in the NFL in passing and they face a Steelers offense that ranks second in passing at nearly 300 yards per game. "I don't think it would be a secret," Childress said about the reasons for the struggles. "Missed tackles will kill you but particularly in air, in space. A guy like Ray Rice is able to elude and bounce off and keep his pads down low. It would be missed tackles and in a couple of instances we had some missed assignments where there's a) a guy is not doing what he should do or b) a miscommunication where everybody is doing one thing and somebody else is doing another thing. We go back through the communication process. … You can't stop every play. Every defense has a strength and weakness. It's just more important for our guys to understand where the strength is and where the weakness is and play to it." In other news, Childress said his level of concern over Percy Harvin's shoulder injury is no different than last week. Harvin left the game after being tackled on a kickoff return and had his arm in a sling after the game. Childress said Harvin was at Winter Park getting treatment on Monday. "He's sore," Childress said. ** Childress said Adrian Peterson has "overall body soreness, as well you would imagine." Update: Winfield was wearing a walking boot on his right foot during media access to the locker room today. He declined to speak to reporters because he was headed to the training room to receive treatment.