The Bills are unlikely to have starting left cornerback Terrence McGee in a week where they're facing the league's fourth-ranked passing offense.
"Terrence did not practice again today and we're going to list him as doubtful," said head coach Dick Jauron Friday.
McGee has been working hard trying to rehab from a sprained knee suffered last Sunday during the first defensive series at St. Louis.
Expected to start in his place is third-year corner Ashton Youboty.
"We'll see who starts at game time, but both Leodis (McKelvin) and obviously Ashton would be the first guy," said Jauron. "He's our nickel and he's played the most football for us at this point."
The only thing that could compromise that would be if the Cardinals lined up in a three-wide formation to start the game. In those situations it's believed that Youboty would move inside to cover the slot, with the rookie McKelvin coming on the field to handle the left cornerback position where he has lined up since the spring OTAs.
Whatever role McKelvin plays on Sunday he's looking forward to the opportunity.
"I have to be ready," said McKelvin. "Terrence (McGee) went down. They have me and another rookie that have to dress this week, Reggie Corner. We only have four corners. Terrence is one of the best defensive backs on the team, so I have to come in and I have to step up and fill in his shoes. I have to come in and live up to expectations I'm supposed to live up to. I'm going to make plays when I can."
Schobel, Stroud questionable
Aaron Schobel and Marcus Stroud have been battling nagging injuries throughout the course of the practice week.
Schobel did not practice on Wednesday, but was out on the practice field Thursday and Friday as he works through an undisclosed foot injury.
Stroud is recovering from a shoulder injury suffered in last week's game at St. Louis. The Bills starting defensive tackle missed only a couple of plays before he returned and finished last week's game.
Head coach Dick Jauron is pretty confident both will be able to go on Sunday.
"They both practiced (Friday), but they were both limited," Jauron said. "I'm pretty optimistic about both of them, but we've listed them as questionable and we'll treat them as game time guys."
It would be almost shocking if Schobel did not play. Schobel has never missed a game in his eight seasons in the NFL. He currently has the longest consecutive regular season games played streak among NFL defensive ends with 116.