Where: Ralph Wilson Stadium, Buffalo, NY (grass, outdoors)
When: Saturday, 1 p.m. ET (CBS)
Spread: Bills by 3
Forecast: Mid-60s, small chance of rain
Records: Chiefs (Overall: 0-1, AFC West: 0-0); Bills (Overall: 0-1, AFC East: 0-1)
Past results: Two most recent meetings -- Sept. 11, 2011: Bills 41, Chiefs 7; Oct. 31, 2010: Chiefs 13, Bills 10. Series record: Bills hold 24-18-1 edge.
What matters: The Chiefs' defense was so bad in the opener against Atlanta that they did not force a punt until midway through the fourth quarter. There was plenty of blame to go around, but the main problem was in the secondary. CB Jacques Reeves, who had not played in the NFL since 2009, started in place of Brandon Flowers. The Chiefs need to make fixes fast -- getting Flowers back would be a start. Ryan Fitzpatrick has fond memories of facing KC's defense, as he threw four touchdowns in a 41-7 win last year. It's important the Chiefs' defense start fast and not let Fitzpatrick play with the kind of confidence Ryan had in picking them apart.
Who matters: OLB Tamba Hali and Flowers. Hali's absence was obvious when watching Ryan sit in the pocket and not worry about Kansas City's best pass-rusher coming around the corner. Fellow OLB Justin Houston recorded Kansas City's only sack and was the only KC defender to put any sort of pressure on Ryan. Hali's return should give Fitzpatrick something to think about, especially with Hali going against Buffalo rookie LT Cordy Glenn. Buffalo is not as talented as Atlanta at receiver, but the dropoff after Flowers is so big his presence should make a big difference. Flowers has been medically cleared to play, and it's his call whether he suits up in Buffalo.
Key matchups: SS Eric Berry vs. Bills WR Steve Johnson. Johnson's cut-block knocked Berry out for the season last year and Berry said on Twitter after that game that the Bills were out to get him. He later said he was joking. Just to be safe, Johnson might want to avoid the middle of the field. Flowers vs. Johnson: This is the matchup that could actually take place and is definitely worth watching. Will Fitzpatrick test Flowers or give him the respect a top corner typically receives? RT Eric Winston vs. Bills DE Mario Williams. Each team's most important acquistion and former teammates will face off Sunday. The Chiefs allowed three sacks against Atlanta -- none were Winston's fault -- and Williams was unable to record a sack in his first game as a Bill.
Injuries of note: NT Anthony Toribio and DE Allen Bailey were both limited participants at practice on Thursday and are questionable for Sunday's game. Both missed the opener against Atlanta. S Kendrick Lewis will not play for the second straight week because of an injured shoulder.
Inside stuff: WR Jon Baldwin was the star of training camp and is expected to take a big leap in his second year. Baldwin was nearly invisible in Week 1 and slot WR Dexter McCluster was the surprise star of the receiving corp. McCluster had a team-high six catches and was targeted 10 times. Unless the Chiefs see a possible mismatch for Baldwin, expect to see more McCluster and less Baldwin.
Connections: Chan Gailey was the offensive coordinator in Kansas City in 2008 and was fired during the preseason of 2009. He took with him to Buffalo former backup QB Tyler Thigpen. Winston and Williams were teammates for six seasons and both part of Houston's 2006 draft class.
Stat you should know: K Ryan Succop has missed four of his last seven field goal attempts in the regular season and missed a 40-yard try against Atlanta. He was two for four in the preseason.
Looking ahead: The Chiefs were one game from making the playoffs last season despite an 0-3 start. They don't want to start in a similar hole this year. Buffalo is as close to a must-win in Week 2 as you get. Why? The Chiefs go to New Orleans next.
Prediction: Chiefs 24, Bills 21
Follow Chiefs reporter C.J. Moore on Twitter @CBSChiefs and @cjmoore4.