Usually it's Bears opponents who have to worry about defending punt returns, given that Devin Hester has an NFL-record 12 for touchdowns.
But Cardinals cornerback Patrick Peterson returned 4 punts for touchdowns last season as a rookie, tying the NFL record that Hester also tied in 2007 and was originally set by the Lions' Jack Christiansen in 1951.
"He's by far the best punt returner that we're going to face all year," Bears special teams coordinator Dave Toub said. "The guy's extremely dangerous."
Peterson hasn't scored this season, and he's averaging 8.6 yards per return, way down from last year's NFL-best 15.9. But the Bears are well aware of his game-breaking ability.
"I didn't have to show a lot of clips before he got the guys' attention," Toub said. "They know going in our hands are going to be full."
For much of the season, Hester has struggled through what has been a down season for returns by his standards. But he's shown signs of breaking out the past two weeks with 100 yards on 8 attempts for a 12.5-yard average.
"He's being more aggressive," Toub said. "Two weeks ago we asked him to be more aggressive to the ball and attack it and show people the real Devin Hester, and he's responding. The last two weeks he's looked good and hopefully he takes even another step this week."
The only time Hester has played against the Cardinals in Arizona, a Monday night game on Oct. 16, 2006, he returned 6 punts for 152 yards, including an 83-yard TD to help spark the Bears' 24-23 comeback victory.
With backup defensive tackle Matt Toeaina (knee) already on injured reserve and starter Henry Melton (chest) doubtful for Sunday, the interior D-line could go into Arizona short-handed. For the second straight game, defensive end Israel Idonije could start in Melton's 3-technique spot.
The linebacker position is also a concern. Brian Urlacher (hamstring) will miss his third straight game. Backup Blake Costanzo (calf), who started his first NFL game last week on the strong side in place of injured Geno Hayes, was unable to practice Friday and is questionable. Hayes went through a full practice Friday for the first time in two weeks and is probable.
Cornerback Tim Jennings (shoulder), offensive tackle Jonathan Scott (hamstring) and wide receiver Earl Bennett (concussion) were all limited and are questionable. Jennings could be back in the starting lineup, but Gabe Carimi is expected to start at right tackle for Scott.
Wide receiver Brandon Marshall (hamstring) and defensive end Shea McClellin are both probable after full practices.
The Cardinals' defense leads the NFL in interception percentage and has picked off 14 passes in its last six games.
The Bears' offense is 30th in avoiding interceptions, including Jay Cutler's 14 picks. But offensive coordinator Mike Tice believes Cutler can avoid costly mistakes if the reshuffled offensive line performs.
"If we give Jay good time, and he's able to set his feet, he's extremely accurate," Tice said. "I think we'll be OK."
Running back Kahlil Bell has only been back with the team since Tuesday, but he could see some action Sunday, especially in short-yardage situations, with Michael Bush on injured reserve.
He carried 12 times for 32 yards in Weeks 3 and 4 before he was released.
"Kahlil knows the offense," coach Lovie Smith said. "He's not like a guy coming in off the street that doesn't know exactly what we're doing. We feel comfortable with him."