The Packers remain in pursuit of a second straight Super Bowl, but regardless of whether they hoist the Lombardi Trophy at the end of the year, they won't be able to claim a perfect season.

Green Bay suffered a stunning 19-14 upset at the hands of the 6-8 Chiefs, who were playing under interim coach Romeo Crennel. The loss dropped the Packers to 13-1, with the defeat being the first suffered by the reigning champions since they lost to the Patriots last December.

In a potentially devastating blow to an already overwhelmed Patriots defense, Andre Carter had to be carted off after injuring his left knee on the final play of the first quarter in Denver. The team confirmed moments later it was a knee injury and that he would not return. 

The Patriots announced before Sunday's game that offensive lineman Nick McDonald and third quarterback Ryan Mallett will be the final two inactives for the Patriots today against the Broncos. 

McDonald, a second-year player out of Grand Valley State, served as a back-up center the last two weeks. Dan Connolly returns to starting center from a strained groin that forced him to sit the last three games. Ryan Wendell (calf) is also available to play center, as he did in the second half last week against Washington. 

The Patriots announced Saturday afternoon that five players have been downgraded to out for Sunday's game against the Broncos in Denver: safety Patrick Chung, running back Shane Vereen, linebacker Brandon Spikes, offensive lineman Sebastian Vollmer and wide receiver Deion Branch.

Here are the 10 matchups we’ll be looking for in Sunday’s game between the Patriots and Broncos.

The Patriots have signed linebacker Jerod Mayo to a five-year contract extension, according to ESPN's Adam Schefter. The 25-year-old Mayo, who was the 10th overall pick in the 2008 draft, has been a defensive mainstay since he first arrived in Foxboro, and had his best season last year when he registered a career-best 175 tackles. The performance was good enough to land him an All-Pro berth and a spot in the Pro Bowl. He was recently named the 62nd best player in the game in an NFL Network countdown of the Top 100 players in the game, a list voted on by the players.

Patriots safety Patrick Chung did not travel with the rest of his team to Denver for Sunday's game against the Broncos. Instead, he was sitting courtside at the Celtics scrimmage at TD Garden on Friday evening.

Chung, who did not practice this week, was listed officially as "doubtful" for Sunday's game. The third-year safety has been limited to seven games this year; he has not played in a game since Nov. 6 due to a foot injury. He has 55 tackles (36 solo), an interception and a sack this season.

According to multiple reports, Patriots defensive lineman Andre Carter was fined $15,000 for hitting Redskins quarterback Rex Grossman below the knees in New England's 34-27 victory last Sunday. Carter was flagged on the play, and the fine is his second of the season. However, just as he did when he was fined $15,000 for a hit on Chargers quarterback Philip Rivers earlier in the season, Carter told reporters that he plans to appeal the fine.

The 32-year-old Carter leads the Patriots with 10 sacks this season, including one against the Redskins.

FOXBORO --  After being listed as limited for non-injury related reasons on Wednesday and Thursday, Tom Brady and Vince Wilfork were officially taken off Friday's practice participation report. The only two players to miss practice this week - Patrick Chung and Sebastian Vollmer - were both listed as doubtful for Sunday in Denver as the team left Friday afternoon for their game against Tim Tebow and the Broncos. All 13 players listed as limited on Friday were classified as "questionable" for the game. Friday's complete Patriots injury report is as follows:

FOXBORO -- For the third straight day, Patrick Chung and Sebastian Vollmer were the only Patriots not at practice as the team continues preparing for Tim Tebow and the Broncos this Sunday in Denver. 

With wind whipping up to 35 miles per hours outside, the team went indoors to the Dana Farber Field House and held their third straight practice in sweats and shells. The team did not practice in pads this week. 

The Patriots leave late Friday afternoon for Denver, taking off a day early to adjust to the time change.