Denver Broncos quarterback Peyton Manning has a bum ankle. The Kansas City Chiefs have played the NFL's weakest schedule. The Seattle Seahawks have had trouble protecting Russell Wilson with a banged-up offensive line. And these are just problems bugging the teams widely considered to be the best in the NFL.
In this season, perhaps more than any in recent memory, there is no perfect NFL team, no team that has proved dominant on a weekly basis, and certainly no sure thing to make it to the Super Bowl. It's all setting up a wild rest of November and December, starting with Sunday's game between the Chiefs and Broncos.
But which flaws are temporary blips, and which could prove fatal?
Flaw: The Broncos are struggling to protect Peyton Manning.
Quarterback Peyton Manning was sacked only five times in Denver's first six games, but has been sacked eight times in the last three games. All those hits are taking a serious toll on Manning's health. Manning's sprained ankle won't keep him out of Sunday's game against Kansas City, but let's not forget that his ankle is, indeed sprained. With Manning ailing, how many more brutal hits can he endure?
How serious is it? There is no magic fix to the Broncos' offensive line, because All-Pro left tackle Ryan Clady isn't coming back this year. If the Broncos are going to make it to the Super Bowl, it will be with Chris Clark at left tackle. Denver's coaches must find a way to help Clark out more, while the pressure is on Manning and Denver's receivers to hit on quick passes to slow the pass rush.
Upcoming test: The offensive line will get its biggest challenge this week against Kansas City, which leads the NFL with 36 sacks (an average of four per game). The Broncos will have to account not just for pass rushers Tamba Hali and Justin Houston on the edges, but interior pressure by Dontari Poe.
Kansas City (9-0)
Flaw: Can they hang when the schedule gets tough?
The Kansas City Chiefs have the league's best record in large part because of a defense that's holding opponents to just 12.3 points per game - easy enough when opposing quarterbacks are guys such as Blaine Gabbert, Case Keenum, Jason Campbell, Jeff Tuel, Ryan Fitzpatrick Terrelle Pryor. None of the teams the Chiefs beat in the first half of the season have a winning record. Will the Chiefs be able to score enough points once they have to face teams with better starting quarterbacks?
How serious is it? If defense really does win championships, this could just be a minor flaw, as long as the Chiefs defense can continue to contribute points - like their four pick-sixes in the first nine weeks. But at some point, the Chiefs offense, led by Alex Smith and running back Jamaal Charles, will need to be more than safe.
Upcoming test: We'll find out in the next three weeks if Smith and the offense can keep up with elite quarterbacks, with a pair of games against Peyton Manning and the Broncos and a home game against Philip Rivers and the San Diego Chargers.
New England (7-2)
Flaw: Depleted defense
First, the Patriots lost defensive tackle Vince Wilfork, and then it was inside linebacker Jerod Mayo - both out for the season. Then cornerback Aqib Talib missed time in October with a hip injury. Just how many dings to defensive stars can the Patriots survive?
How serious is it? Tom Brady and the Patriots offense exploded for 55 points in their last game before the bye week. That sort of powerful attack will cure all sorts of defensive deficiencies, and the Patriots have made deep postseason runs with a mediocre defense before. If Talib is able to return quickly - starting with New England's Monday game at Carolina, the Patriots defense will quickly look a lot more formidable.
Upcoming test: As much fun as it is to think about Tom Brady vs. Peyton Manning (with new sidekick Wes Welker) when the Broncos visit Foxborough on Nov. 24, Manning and the Broncos will really be testing that battered New England defense. Will the Pats have enough bodies to defend Welker, Demaryius Thomas, Julius Thomas and Knowshon Moreno?
Flaw: Too reliant on Andrew Luck's fourth-quarter magic
Maybe the Colts were getting comfortable in believing there was no such thing as a second-half deficit too large for Andrew Luck to overcome. Then came Sunday's 38-8 beatdown by the Rams to reveal some significant concerns about the Colts' ability to rally when Luck is just off. The Colts have beaten the Seahawks, 49ers and Broncos - three statement wins if there is such a thing - but the losses to St. Louis, San Diego and Miami might speak even louder.
How serious is it? The Colts, provided they can beat Tennessee this Thursday, should have little trouble winning the AFC South, and might be able to look back later on Sunday's disaster against the Rams as just a small speed bump.
Upcoming test: Given their trouble with the Rams, the Colts should be wary of the Arizona Cardinals, whom they play Nov. 24 in Glendale. Then there is the Dec. 22 game at Arrowhead Stadium against the Chiefs - perhaps the biggest test for Luck and the Colts offense since the Seattle game in early October.
VIDEO: Week 11 story lines
Flaw: Missing pieces on offense
How many teams can survive the loss of not just one offensive tackle, but two? Seattle has managed to do that for weeks since left tackle Russell Okung landed on short-term injured reserve with a foot injury and right tackle Breno Giacomini injured his knee. Center Max Unger has also been sidelined with a concussion. Those injuries, as well as a season-ending knee injury to receiver Sidney Rice and the prolonged absence of Percy Harvin, have put even more pressure, both literal and figurative, on second-year quarterback Russell Wilson.
How serious is it? As if a three-game lead in the NFC West by early November wasn't enough good news for the Seahawks, Seattle knows it's getting healthy. Okung and Giacomini and Harvin are all back at practice, and the Seahawks' offense could be nearly at full strength after it returns from its Week 12 bye week.
Upcoming test: There might be no better game on the December calendar than the Dec. 2 Monday Night game between the Saints and Seahawks at CenturyLink Field, where the Wilson will try to out-duel Drew Brees. Let's just call it a playoff preview.
Flaw: Cam Newton's consistency
There is little question Cam Newton has recovered well from a disappointing 2012 season. He's a better leader, a better passer and in much better command of the Panthers' offense. But is he consistent enough for the Panthers to make a serious playoff push? Newton has completed 55 percent or less of his passes in four of Carolina's games, including going 16-of-32 in the Panthers' 10-9 win against San Francisco last week.
How serious is it? The Panthers have proven they can win even when Newton isn't perfect, and that's very good news. A young quarterback is able to endure plenty when paired with a thriving running game and a stout defense - both of which Carolina currently possess.
Upcoming test: Newton and the Panthers will play the New England Patriots this week, and then have two games against the New Orleans Saints in December. Newton will need to be at his best with Tom Brady and Drew Brees on the other sideline.
New Orleans (7-2)
Flaw: Trouble on the road
Losing to Tom Brady and the Patriots on the road might be one thing. But the Saints' other loss this season came at the New York Jets. New Orleans also won road games at Chicago and Tampa by single-digits, quite the difference from blowing out opponents in the Super Dome.
How serious is it? Those AFC East losses kept the Saints from running away with the NFC South early in the season and have placed much more importance on the back half of the schedule that includes road games in three of the final five weeks, including games with playoff implications.
Upcoming test: Home field advantage in the playoffs could be determined Dec. 2 in Seattle.
San Francisco (6-3)
Flaw: Stagnant passing game
Remember when Colin Kaepernick threw for more than 400 yards against Green Bay in Week 1? Feels like a really long time ago. Even when the Niners went on a five-game winning streak, the passing game was struggling, and Kaepernick has thrown for more than 200 yards only once since that opening game, and he's completing only 56 percent of his passes.
How serious is it? The Niners offense is better when it is run-first with running back Frank Gore. But Kaepernick just has to be better for those inevitable times the offense can't run through Gore, or when the Niners have to play from behind.
Upcoming test: Kaepernick has never beaten the Seattle Seahawks, and has played poorly in the two games against Seattle since taking over as the Niners' starter a year ago. He can try to avoid falling to 0-3 against Seattle on Dec. 8 at Candlestick.