ORCHARD PARK, N.Y. -- The Buffalo Bills just can't get it right in the red zone.

Since the start of last season -- a total of 25 games -- the Bills have been the NFL's worst at scoring touchdowns from inside the 20-yard line, converting on just 44.9 percent of their chances.

Never had the problem been more pronounced than it was in Sunday's 17-13 loss to the Kansas City Chiefs.

This was a game that the Bills' defense controlled from nearly start to finish, affording the offense ample opportunity to score points, open a lead and secure what should have been Buffalo's sixth win of the season.

Instead, the Bills blew it. In four red zone chances they settled for two field goals, saw Bryce Brown fumble a would-be touchdown into the end zone for a touchback and then failed to convert on a fourth-and-10 from the 15-yard line late in the quarter.

That's why, even though the Bills (5-4) held a 10-3 halftime lead, this game had the feel of a collapse. Nothing Alex Smith and the Chiefs' offense did through the first three quarters inspired confidence, yet, given the Bills' ineptitude in the red zone, Kansas City came away with a win it never should have sniffed.

"I don't want to take anything away from Kansas City. There are obviously some things that we did that -- when you look at how to beat them -- it gives you an opportunity to beat them," Bills coach Doug Marrone said. "We did some of those things but then we hurt ourselves and didn't take advantage of opportunities where we had them."

Call it a flaw exposed. The Bills were one of the NFL's worst offenses in the red zone last season, ranking 29th in the NFL, and entered Sunday's game in that same spot. It's a stubborn problem that -- more than anything else -- stole this win from the Bills' grasp.

"A couple of missed opportunities," quarterback Kyle Orton said. "Which when you're playing a good football team usually comes back to haunt you."

It must be frustrating for Marrone and offensive coordinator Nate Hackett that their unit went 0-for-4 in the red zone Sunday in front of a sellout crowd at Ralph Wilson Stadium. After all, it was that phase of the game that they worked tirelessly to improve in training camp, adding an extra period devoted to the red zone at the end of each practice at St. John Fisher College.

For all of that work in front of a few dozen fans those July and August nights not to pay off in November -- when the season is on the line -- is a troubling sign for a team that has other pieces in place to make the playoffs.

The Bills will have minimal time to correct their mistakes before they travel to play the Miami Dolphins (5-4) on Thursday night.

Lose that game and the Bills will fall back to .500 on the season. With the most difficult portion of their schedule arriving with a trip to Denver on Dec. 7, time is running out for the Bills to clean up their red zone problems, which have plagued them for far too long.

"I don't think it's a secret what happened out there," Marrone said. "We made mistakes and then didn't take advantage of those opportunities.

"We had an opportunity to get to 6-3. Now we're going to have to fight our way back and find a way to win our next game."