SAN FRANCISCO - AUGUST 18: Linebacker Patrick Willis #52 of the San Francisco 49ers during a preseason game against the Oakland Raiders on August 18, 2007 at Monster Park in San Francisco, California. (Photo by Greg Trott/Getty Images)

15 Sep 1991: Linebacker Mike Singletary of the Chicago Bears works against the New York Giants during a game at Soldier Field in Chicago, Illinois. The Bears won the game, 20-17. (Photo by Jonathan Daniel/Getty Images)

LOS ANGELES, CA - MAY 19: Linebacker, Patrick Willis #52 of the San Francisco 49ers at the 2007 NFL Players Rookie Premiere on May 19, 2007 at the Los Angeles Memorial Coliseum in Los Angeles, California. (Photo by Nick Laham/Getty Images)

Linebacker Mike Singletary of the Chicago Bears strips the ball from wide receiver Stanley Morgan of the New England Patriots during the Bears 44-10 win in Super Bowl XX at the Superdome in New Orleans, Louisiana. (Photo by Mike Powell/Getty Images)

SANTA CLARA, CA - JULY 29: Linebacker Patrick Willis #52 of the San Francisco 49ers works out during training camp on July 29, 2007 in Santa Clara, California. (Photo by Greg Trott/Getty Images)

CHICAGO - NOVEMBER 13: Asst. Head Coach Mike Singletary of the San Francisco 49ers make his first appearance as a coach against his old team, the Chicago Bears on November 13, 2005 at Soldier Field in Chicago, Illinois. (Photo by Jonathan Daniel/Getty Images)

PITTSBURGH - SEPTEMBER 23: Patrick Willis #52 of the San Francisco 49ers knocks the ball loose from Hines Ward #86 of the Pittsburgh Steelers on September 23, 2007 at Heinz Field in Pittsburgh, Pennsylvania. Pittsburgh won 36-17. (Photo by Rick Stewart/Getty Images)

10 Sep 1989: Linebacker Mike Singletary of the Chicago Bears looks on during a game against the Cincinnati Bengals at Soldier Field in Chicago, Illinois. The Bears won the game, 17-14. (Photo by Jonathan Daniel /Allsport)

CHICAGO - OCTOBER 18: Linebacker Mike Singletary #50 of the Chicago Bears prepares for a play as he looks over the Tampa Bay Buccaneers offense during a game at Soldier Field Stadium on October 18, 1992 in Chicago, Illinois. The Bears won 31-14. (Photo by Jonathan Daniel/Getty Images)