Here's a look at a key matchup heading into Sunday's battle between the Bears and Seahawks at Soldier Field.

Seahawks WR Mike Williams vs. Bears CB Charles Tillman

Williams, the Seahawks' top receiver, racked up 123 yards on 10 catches against the Bears on Oct. 17, and while Tillman wasn't the only member of the secondary who struggled that day, he was covering Williams for much of the game.

Head coach Lovie Smith acknowledged this week that his defense has to do a better job of covering Williams this time around, and it's clear Williams, one of the league's more improved players, has Chicago's attention. The Bears are not going to say if they plan on changing their usual coverage schemes in order to limit Williams, but Smith isn't one to stray too far away from his cover-2 "D."

Tillman is Chicago's best corner and he has good size for his position. That didn't help him much against Williams, though. The fourth-year receiver is about four inches taller and 40 pounds heavier than Tillman and, while speed isn't his strength, he's quick enough to leave Tillman behind.

A more disruptive performance from the Bears' pass rush, which failed to sack QB Matt Hasselbeck in Week Six, would give Hasselbeck less time to throw and aid Tillman as he attempts to keep Williams from going off.