It's probably not surprising that Sunday night's key AFC battle between the Patriots (10-0) and Broncos (8-2) in Denver includes a quarterback who's the reigning AFC Offensive Player of the Week.

That the quarterback in question is new Denver starter Brock Osweiler - he of one career NFL start in which he earned the honor in a victory in Chicago - and not future Hall of Famers Tom Brady or Peyton Manning is where the intrigue in the Rocky Mountains crystalizes like fresh fallen snow, which is actually a weather possibility this week.

The world is well aware at this point that what was supposed to be a primetime showing of Brady vs. Manning XVII has turned into the far-less-marketable Brady vs. Osweiler I.

Manning is in a walking boot and sidelined to injury for at least the next few weeks. Given his performance this season as arguably the worst quarterback in football, No. 18's absence could become permanent.

What's left, though, is still a very interesting game among two of the better teams in the conference trying to get through major injury issues. Now, it's a battle of the NFL's top two scoring defenses, New England No. 1 in points allowed and Denver at No. 2.

That the Broncos unit with Von Miller, Aqib Talib and the rest is among the best in the game is probably no surprise at this point. But, the fact that Chandler Jones, Malcolm Butler and the rest in New England are atop the statistical rankings at this point is far more unforeseen.

So an unforeseen defense will try to stop a young, inexperienced, unforeseen starting quarterback.

On the other side, Brady will try to adjust on the fly to a group weapons that are dropping like flies due to injuries.

It's not the story or the game we thought we'd be seeing unfold in this holiday weekend duel in Denver, but it's an extremely interesting matchup all the same.

Here are a few key aspects to keep an eye on heading into this key AFC affair that includes a greater focus on defense and one less future Hall of Fame passer than was expected:

Let's go pass pro - New England's offensive line has been a major storyline, for better and worse, throughout the season. The group has had to deal with injuries and endless personnel movement while facing some pretty formidable challenges from opposing defensive fronts along the way. That will continue in Denver against an impressive Broncos front that leads the NFL with 34 sacks, including multiple sacks from nine different players. The Patriots got veterans Marcus Cannon and Sebastian Vollmer back from injury last week, but neither played particularly well. Cannon was especially bad at left tackle, struggling in a matchup with Jerry Hughes. The line faces two questions in this trip to Denver: what will the lineup look like and will they meet the challenge the Broncos front seven defenders represent? In theory Vollmer is a more prototypical left tackle, while Cannon's best play as a professional has come on the right side. That would appear to be the better lineup, but for some reason New England chose not to go that direction against the Bills. And while DeMarcus Ware and his Broncos-high 6.5 sacks have been sidelined in recent weeks (and practice this week) with a back injury, Von Miller (6 sacks) has always been a thorn in Brady's side. There is also uncertainty on the interior line as Bryan Stork replaced David Andrews during last week's win over Buffalo and could reclaim his starting job at center. However the unit is deployed it must perform better. Brady simply can't be hit as often and as hard as has been the case the last two weeks, including 10 QB hits against Buffalo. If anything the Patriots passer needs more time to deal with the issues and alterations to his core of targets. The line must be better in this big time road challenge.

Brock talk - All the world knows everything there is to know about Manning. But that knowledge is irrelevant to this game. Osweiler is the man for the Broncos. He has thrown 81 passes in his three-plus year NFL career as a former second-round pick out of Arizona State. He completed 20 of his 27 throws in Chicago with a pair of touchdowns and no picks for a 127 rating. He was sacked five times, though. Despite his look of a statuesque pocket passer given his 6-7, 240-pound frame, Osweiler is mobile enough to run the bootleg passes that Broncos head coach Gary Kubiak so covets. The young passer lines up under center, as well. So while the Broncos have just the 27th-ranked rushing attack (3.9-yard team average on the year) and are facing the Patriots No. 2 rush defense, don't be surprised if Denver runs early to try to balance out its offense and set up the play-action passing game and boots. Osweiler's inexperience and the Broncos injury-depleted offensive line should give Chandler Jones and the Patriots pass rush a chance to get home. But the young passer is also an intriguing new weapon for the Broncos and it will be interesting to see how he does against a still-questionable Patriots pass defense and his first crack at a Belichick game plan.

Moving targets - Three of Brady's top four productive pass catchers this season potentially won't be in Denver. That means Brady needs to find other targets to make plays, but there are certainly options for him to do just that. Gronkowski simply needs to be better. He was held in check last week by the Bills. Despite increased attention, the All-Pro needs to up his game. And Brady may need to throw to him even when he's theoretically covered. Brandon LaFell is also due for an increased role as he rounds into midseason form after opening the year on PUP. He was a key trusted target and drive starter a year ago, a role he needs to fulfill once again with the likes of Julian Edelman and Dion Lewis out of the question and Danny Amendola's status (knee) in doubt. The third guy who'll need to see his role grow is James White. The second-year passing back had his first two career touchdowns last week, maximizing his four touches in helping key the Patriots victory. Brady and Josh McDaniels need to have the confidence to allow White's role grow. He's not the same player as Lewis, but he's shown the ability to contribute and likely needs to be given more chances to do so against the NFL's No. 1 pass defense. There is no doubt Brady's offense is going through a transition. The group has lost a lot of talent and hasn't run the ball well in recent weeks. As such, guys need to step up in the passing game. Gronkowski, LaFell and White are far from a bare cupboard of options. They need to get the job done, maybe even in some spread sets similar to what the offense was doing with Lewis in the middle of it all in early season success. The reality is that the Broncos are very good on defense, but the Patriots still have the potential to be very good on offense even in this tough spot.

Rocky Mountain horror shows - There aren't many places on the planet where Belichick and Brady fail to succeed with regularity. But the Mile High City is one of those places. New England is just 2-5 in Denver dating back to 2001. They've lost to a variety of coaches and quarterbacks in the Rocky Mountains. Even though Belichick downplayed the idea of altitude being an issue this week, maybe that does have something to do with it. Maybe not. For the here and now it's more likely that Denver's impressive defense and New England's offensive injuries would play into Broncos win. Really New England's struggles in Denver pre-date the Belichick/Brady era. The Patriots are 9-19 in the 28 all-time road games against the Broncos. A popular light beer may be brewed in the Rocky Mountains, but it hasn't been a place to brew up much Patriots success over the years. Sunday night we'll find out if the history of troubles in Denver continue.

Butler service - Malcolm Butler hasn't been perfect this season, but there is little question the second-year Super Bowl hero has solidified his role as the Patriots No. 1 cornerback. The depth behind him at the position has been very much tested of late. Logan Ryan is the No. 2 cornerback, but a hand injury to Justin Coleman and poor play by Rashaan Melvin caused the team to use extra safeties in the nickel and dime roles against Buffalo. Denver's top playmaking pass catcher is Demaryius Thomas - team-high 71 catches for 875 yards - especially with Emmanuel Sanders limited of late with ankle and finger injuries. A couple weeks after Butler had a great battle with New York's Odell Beckham Jr., he made need to do it again against Thomas. While the Patriots will likely throw a lot of different looks and schemes at the young, inexperienced Osweiler, Butler needs another big day to help the back end continue to get by against what will be a new-look Broncos offense likely to take some play-action shots down the field. The Patriots have certainly had issues allowing big pass plays at times this season - and gotten away with guys wide open deep at times that didn't end up hitting for a big play - and cleaning up that area in Denver would be a nice start to stopping the Broncos aerial attack. Butler, and veteran safety Devin McCourty, are the first two key cogs in getting that done.

What a run - New England's run defense has been the most consistent aspect of the entire team for more than a month. On paper the Broncos rushing attack isn't that formidable, but that could change with Osweiler under center. Denver had a season-high in carries (36) and rushing yards (170) in the young quarterback's first start in Chicago. That type of increased focus on the ground game is likely to continue. So it's up to the Patriots No. 2 rushing defense to do what it's done for the last five straight games and force the opponent to throw. New England's front, led by Dont'a Hightower, Alan Branch, Malcom Brown and the rest has held opponents to 3.5 yards per carry or less in each of the last five games. None has topped 100 yards on the ground. The challenge this week is clear - stop Denver's zone-blocking rushing attack. That puts an emphasis on the outside defenders to set the edge against the Broncos outside zone runs. It will be a key team effort up front to stop the run and make Osweiler get the job done without the yards on the ground or the play-action/boot pass plays that come as a result to early success in the running game. The Patriots run defense has been superb and probably needs to remain that way in this one.

Prediction - There is no doubt the Patriots have struggled a bit to remain undefeated over the last few weeks. Injuries are an issue right now. It is what it is. Heading to Denver in the current state on a short, holiday week is theoretically a pretty tough spot for New England. But the Broncos are a bit of an unknown with Osweiler at the helm. There are really a lot of uncertainties in this game for both teams, more than might be expected of two of the better teams, both by record and statistics, at this relatively late point in the season. But a doubted Brady and his passing attack are dangerous. No. 12's probably aware that many are doubting what he and his targets can do against the NFL's No. 1 pass defense. Given that, it's easy to see Brady with a little extra juice on the road Sunday night and one of his emphatic post-touchdown or post-run celebrations. Make no mistake, the Broncos coverage and pass rush will make it hard on Patriots. But look for Brady to make enough plays, on long drives, led by plays to the likes of Gronkowksi and White, to move the ball. It's imperative to avoid turnovers and potential defensive scores/field position. The Patriots run defense will be expected to do its job and then the pass defense will have to be what it's been all year - good enough. I can see that against a young quarterback. Toss it all together and this feels like something in the range of a 24-13 Patriots road win. But, as we often say on the PFW in Progress radio show on Patriots.com heading into tough games, I am mentally prepared for the possibility of a New England loss. The margin of error has been greatly reduced. But when the going gets this tough, Belichick's teams often get going.

What other things will you be watching for in this Sunday night as the world's eyes focus on the Mile High City as two supposed Super Bowl contenders try to once again prove their mettle? Let us know with a comment below!