LAKE FOREST, Ill. (AP) -- Chicago Bears strong safety Mike Brown is out indefinitely after undergoing surgery to repair ligament damage in his right foot Wednesday, a major hit for the NFL's second-ranked defense.
Brown limped off the field and was taken from the sideline on a cart during the fourth quarter of Monday's 24-23 comeback victory at Arizona after his foot got twisted on a running play.
"Severe blow," coach Lovie Smith said. "I think we all know what Mike means to our football team. He's a special player. He was having an outstanding game. ... That's a big blow, but injuries do happen. Mike has been in this situation before."
Smith wasn't sure if Brown, a Pro Bowl pick last season, would be placed on injured reserve.
Brown played a key role as the Bears rallied from a 20-point deficit against the Cardinals.
The comeback began when he scooped up a loose ball after Mark Anderson sacked Matt Leinart at the end of the third quarter. Brown returned it 3 yards for a touchdown that made it 23-10. Charles Tillman returned a fumble 40 yards for a touchdown after Brian Urlacher ripped the ball from Edgerrin James in the fourth quarter, and Devin Hester put Chicago ahead when he ran a punt back 83 yards.
Finally, Arizona's Neil Rackers missed a 41-yard field goal with 53 seconds left, and the Bears celebrated, jumping around and pointing toward the sky. They were relieved and overjoyed. They improved to 6-0 with a bye this week, but the good vibe was tempered by Wednesday's news.
Brown is one of their emotional leaders, and they have not played well when he has been sidelined in recent seasons.
Brown missed 14 games with a torn right Achilles' tendon in 2004, and the injury-ravaged Bears went 5-11. With Brown nursing a strained calf late last year, the league's stingiest defense looked rather average. The Bears split the final four regular-season games, and with Brown seeing limited time in the playoff loss to Carolina, the Panthers' Steve Smith caught 12 passes for 218 yards and two long touchdowns.
"There's only one Mike Brown that has those qualities as a leader," Smith said. "What we need is to have a good football player step up and fill the role. Brian Urlacher, Adewale (Ogunleye), Alex Brown -- they'll take more of a leadership role."
Can the defense withstand this loss?
"It has to," Smith said. "We have to pick it up."
Brown's injury leaves the Bears thin at safety. Backup Chris Harris has missed three of the past four games with a pulled quadriceps and a sprained ankle. Brandon McGowan was suspended by the team for a week for violating a team rule, but is expected to be back Monday.
Brown's injury could mean more playing time for Todd Johnson, who replaced him on Monday, and Cameron Worrell.
"The encouraging thing is we have guys who can step in and make plays for us," cornerback Nathan Vasher said.