FOXBOROUGH, MA (AP) — The New England Patriots are about to find out if momentum means anything in an NFL season.

The defending Super Bowl champions have lost four of their past six games as they head into Saturday’s playoff game against Kansas City. One more loss, and that’s the end of their quest to be the first back-to-back champions since they did it in 2003-04.

To stick around, they’ll have to snap the Chiefs’ 11-game winning streak — 10 straight to end the regular season and a 30-0 playoff victory over the Houston Texans on Saturday.

“They’ve been playing at an extremely high level. But at the end of the day it’s not really about momentum,” Patriots special teamer Matthew Slater said.

“It’s about executing on Saturday. And whatever team executes better and makes more plays is probably going to leave the game happy.”

The Patriots (12-4) have been the league’s best finishers since Bill Belichick arrived in Foxborough: Since 2001, they are 54-10 in December — eight wins better than the next-best team.

The team’s record in January and February hasn’t been bad, either: Four NFL titles, six trips to the Super Bowl and nine to the AFC championship game under Belichick and quarterback Tom Brady.

But this season they lost twice in December for the first time since ’02, then dropped the regular-season finale in January to finish with a two-game losing streak.

Associated Press-Chandler Jones

“We just haven’t played the way we would’ve liked here these last six games,” Slater said. “We’re very spoiled because we’re accustomed to having a certain level of success in December and January. But every year is different, every team is different, and I think we’re just fortunate and excited about being in the position that we’re in at this point.”

Defensive back Devin McCourty said to look no further than Green Bay, which won its first six games and played below .500 from there, losing its last two games to stumble to a 10-6 record. The Packers eliminated Washington in the wild-card round on Sunday.

“When you turn the page and you go into the playoffs, you’ve got to win that night, that day, go out there and beat another team,” McCourty said.

“Kansas City coming off the 10-game winning streak in the regular season, they looked just as good against Houston playing good football. And I think that’s more important than the so-called momentum is.”

The Chiefs (11-5) won just one of their first six games this season, falling to the brink of elimination before Halloween.

Quarterback Alex Smith said knowing the next loss could knock them out of the playoffs has motivated his team since October.

“You’re living in the right now. It’s no different this next week,” he said. “I don’t think the attitude changes. And, to be honest, I think we been playing like that for a while now. It’s all we know, a little bit.”

WATCH: KEYS TO THE GAME

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No Brown for Pittsburgh

The Steelers won't have All-Pro receiver Antonio Brown when they face the Broncos on Sunday in their AFC Divisional playoff game. He has been ruled out as he recovers from a concussion.

Brown left last weekend's wild-card win over Cincinnati after taking a shot to the head from Bengals linebacker Vontaze Burfict (VAHN'-tez BUR'-fihkt).

It's a big loss for the Steelers as the four-time Pro Bowler tied for the league lead with 136 receptions and was second in yards receiving with 1,834 this season.

Steelers quarterback Ben Roethlisberger (RAWTH'-lihs-bur-gur) remains questionable for the game as he is dealing with a sprained right shoulder.

League comes down on Steelers, Bengals

The NFL has fined four players and two coaches a total of more than $83,000 for their actions in the Pittsburgh-Cincinnati wild-card game last Saturday.

Bengals cornerback Adam "Pacman" Jones was fined nearly $29,000 for contact with an official, while teammates Wallace Gilberry and Domata Peko were each fined about $8,700. Gilberry's fine was for unsportsmanlike conduct and Peko's for unnecessary roughness.

Steelers guard Ramon Foster was fined over $17,000 for unnecessary roughness, and Pittsburgh assistant coaches Mike Munchak and Joey Porter were each fined $10,000.