By Dan Durkin--
(CBS) The Bears (1-3) are seeking their first road win when they face the Chiefs (1-3) in Kansas City on Sunday (noon, Fox).
John Fox coached against Andy Reid's Chiefs twice a year the past two seasons, so he's familiar with the scheme and personnel.
Here are a few storylines to focus on during Sunday's action.
What to watch for when the Bears have the ball
Spreading the Chiefs out
The winning formula for opposing offenses against Kansas City's defense has been using three- and four-receiver personnel groupings in spread sets. The Chiefs' secondary has poor depth, so teams have forced them into nickel and dime sub packages and attacked them from the slot.
The Chiefs have allowed a league-high 11 passing touchdowns, are giving up 296 passing yards per game (28th in the league), and opposing quarterbacks have posted an average passer rating of 106.5 (27th in the league).
Their top cover corner, Sean Smith, returned last week from his three-game suspension. But they lost their other top cornerback, Phillip Gaines, in Week 3 for the season to an ACL injury.
Bears receiver Alshon Jeffery was a limited participant in practice Wednesday as he recovers from his hamstring injury. If he returns, he'll draw Smith and open opportunities inside for Eddie Royal and Marquess Wilson to work against Marcus Cooper, rookie Marcus Peters and Tyvon Branch.
Establishing the line of scrimmage
As much as the Chiefs' secondary has struggled this season, their defensive front it legit. They have stout defensive line anchored by nose tackle Dontari Poe and three talented linebackers -- outside linebackers Justin Houston and Tamba Hali and inside linebacker Derrick Johnson.
Houston notched 22 sacks last season, falling just short of the NFL single-season record. He primarily rushes from the left, so Bears right tackle Kyle Long faces another stiff challenge, as Houston can win with both speed and power.
Not only does this front rush the passer well, but it fits the run aggressively downhill and is disciplined with backside contain.
The Bears rank 11th in the league in rushing yards per game (123), while the Chiefs' run defense ranks 14th (101 yards per game). The Chiefs defense has yet to allow a running back to rush for more than 62 yards.
The depth of the Bears' offensive line has been tested early on. Whichever combination they line up this Sunday must be assignment-sound and clear in their communication, especially if rookie center Hroniss Grasu is thrust into the starting lineup.
What to watch for when the Chiefs have the ball
Defending the screen game
Running back Jamaal Charles is one of the league's most explosive backs, and Reid finds many ways to get the ball into his hands in space. Charles' 20 receptions rank second in the league for running backs, and his 136 yards after the catch rank eighth overall.
Charles is an excellent route runner with soft hands, but the Chiefs also execute the league's most diverse screen scheme. Reid has a knack for calling these when teams bring pressure, which has led to some explosive pass plays.
Under defensive coordinator Vic Fangio, the Bears have played primarily man coverage, which plays right into the hands of a well-timed screen. As defenders have their backs to the ball, teams can slip linemen to the perimeter and build a sidewalk.
Bears inside linebacker Christian Jones in particular must read his keys and show block recognition to lead him into the flats as the primary screen defender.
Quarterback Alex Smith is limited playmaker at quarterback. He functions well within Reid's quick-passing system, which uses bunched sets and pre-snaps shifts and motions to get free releases and better matchups. However, he can't drive the ball down the field and is most comfortable with half-field reads.
As such, the Chiefs heavily utilize play-action to get the ball deep in the passing game. The threat of Charles keeps defenses honest, but they're likely to pull the ball on a play fake and look for tight end Travis Kelce on an over (deep crossing) route or receiver Jeremy Maclin on deep outs, curls and comebacks.
The Bears played nearly a full half last week with rookies Adrian Amos and Harold Jones-Quartey at safety. Starter Antrel Rolle (ankle) missed practice Wednesday, and the Bears brought back Sherrod Martin and activated Demontre Hurst from the practice squad roster.
The Bears' safeties can't get caught with their eyes in the backfield and lose sight of Kelce or Maclin. Both players can take a short throw and turn it into an explosive gain.
Dan Durkin covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter @djdurkin.
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