Here are five things to watch on Sunday:

1. Alex Smith's demeanor inside the pocket

For the third consecutive game, the Chiefs offense will face a defense that consists of some of the top players in the NFL along the defensive line.

Against the St. Louis Rams it was Aaron Donald and Robert Quinn, last week it was Sheldon Richardson and Muhammad Wilkerson for the Jets and this week for the Bills it's the foursome of Jerry Hughes, Kyle Williams, Marcel Dareus and Mario Williams.

These four players combine for an investment of more than $155 million for the Bills, and that's paid off as the Bills rank second in the NFL with 28 sacks so far this season.

For the Chiefs, one thing that's always praised about Alex Smith is his calmness inside of the pocket and his ability to make good decisions in the midst of chaos.

Chiefs coach Andy Reid praised Smith's ability to hang inside the pocket, which he showed last week against the Jets on the 12-yard touchdown pass to Travis Kelce on third down, where he took a pretty good shot after the throw.

Reid said the ability to hang in the pocket is more mental than anything.

"I think you can work on it, but you also must have the courage to do it," Reid said of that ability. "[Alex] is a tough kid."

The Chiefs have been adept to throwing the ball quickly within Reid's offense, but there are still times when Smith has to buy some time and hang in the pocket. On Sunday against a fierce defensive line, the calmness Smith shows amidst chaos will be something to watch for as a key determinant for offensive success for the Chiefs.

2. Strength vs. strength in key area

The Chiefs are one of the best offenses in the NFL at converting on third down, and the Bills defense is one of the best in the NFL at not allowing third-down conversions.

The Chiefs offense has converted 51.9 percent of third downs this season, which ranks second in the NFL. The Bills defense has only allowed 36.2 percent of third-down conversions this season, which ranks fifth in the NFL. 

This will arguably be the most important statistical area to watch throughout the game on Sunday. Smith and the Chiefs offense have been good at matriculating the ball down the field this season. But going up against a stout defense and one that's particularly good in such a key area puts even more focus on this area.

"It's important each and every week," offensive coordinator Doug Pederson said of the strength versus strength matchup. "It just so happens [Buffalo] is really good on third down. The cut-ups we have on third down, there's a lot third-and-long situations, so teams aren't really putting themselves in those short third-down situations, so we continue to do our job on first and second down."

Because there are several different Bills in that front that can create problems, the Chiefs won't have the luxury of double-teaming one particular guy or chipping just off one side with either a running back or tight end. They'll be in some one-on-one situations.

"Buffalo's good because they'll add that backer and then you create one-on-one blocking up front," Pederson said. "Then they do a stunt with the line games. [Kyle Williams] and [Marcel Dareus] become very active. [Jerry Hughes] is very active. [Mario Williams]—when he wants to bring it he can bring it. They're all tremendous football players.

"Our guys, they're honed in on that. It's a great challenge but yet it's one that I know our guys are up for and they're looking forward to this matchup because this is a very good and talented defensive team."

3. Red zone battle

Another key area to watch in this game is when either team gets inside the red zone, an area the Chiefs have been fantastic in on both sides of the ball this season.

The Chiefs offense is scoring touchdowns on 71.4 percent of drives inside the red zone, which ranks fourth in the NFL. Defensively, they're allowing touchdowns on just 50 percent of those same drives, which ranks fourth in the NFL as well.

For the Bills, they've struggled in the red zone on both sides of the ball.

The Bills are scoring touchdowns on just 46.7 percent of drives inside the red zone, which ranks 29th in the NFL. Defensively, they're allowing touchdowns on 63.4 percent of those drives, which ranks 24th.

If the Chiefs can keep up these trends on Sunday, they should find success.

4. Ailing Bills offensive playmakers

Two of the most important pieces to the Bills offense are question marks going into this game.

Veteran running back Fred Jackson is dealing with a groin injury suffered a couple of weeks ago and is still trying to work his way back, but there are no guarantees that he'll be ready to play on Sunday.

The 33-year-old Jackson has 55 carries for 239 yards and a touchdown this season on the ground, also adding 33 receptions for 261 yards and a touchdown in the receiving game.

Considering CJ Spiller is already out with a broken collarbone, Jackson was already trying to shoulder the load of the missing Spiller.

On the outside, Sammy Watkins, the Bills' rookie wide receiver and No. 4 overall pick in the 2014 draft is dealing with a groin injury suffered at practice on Wednesday.

Watkins is leading the Bills in targets, receptions, yards and touchdowns this season.

The potential loss of Jackson and Watkins would be a big loss for the Bills' passing game, which has been doing well with veteran Kyle Orton under center over the past four games (3-1). But you have to believe they're going to do all they can to get Watkins and Jackson healthy and ready for the game on Sunday.

Two players that are healthy and have been playing well for the Bills are receiver Robert Woods, who is second on the team with 294 receiving yards and two touchdowns, and also tight end Scott Chandler, who has 23 receptions for 290 yards and a touchdown as well.

5. Special teams continuing to provide spark

Over the past two games, the Chiefs have seen a spark from the kick return game. Two weeks ago it was Knile Davis' 99-yard return for a touchdown that sparked a second-half rout of the St. Louis Rams.

Last week against the Jets, De'Anthony Thomas' 78-yard return late in the first half set up a key Travis Kelce touchdown reception with under a minute remaining that extended the Chiefs lead to 21-7.

If the Chiefs can continue to get something out of their return game and give the offense a short field to work with combined with the success the offense is having in the red zone, those scores could be the difference in a win or a loss moving forward.

Whether it's De'Anthony Thomas or Knile Davis, the Chiefs special teams under coach Dave Toub have proven to be successful with any number of guys returning the kicks. Cairo Santos has hit nine consecutive field goals and Dustin Colquitt continues to give opposing offenses long fields to work with.