ENGLEWOOD, Colo. -- The Bills rank among the NFL's top 10 in virtually every meaningful category on defense.

Go down the list -- total yards (fifth), yards per play (second), points per game (second), interception rate (fourth), sack rate (first) or third-down percentage (first) -- and it's difficult to find something defensive coordinator Jim Schwartz's unit isn't good at.

"Like most defenses, it starts up front, and theirs is no different," Head Coach John Fox said Wednesday.

Buffalo's D doesn't just conform to that model -- it might be the leading example.

Just looking at draft pedigrees, the talent is apparent: Three of the Bills' four starting D-linemen were first-round picks, and two of those were top three selections (Mario Williams, first in 2006; Marcell Dareus, third in 2011). Kyle Williams, who was taken in the fifth round of the '06 draft, isn't exactly a slouch -- he has as many Pro Bowl appearances as the more heralded Mario Williams (three) and collected 10.5 sacks a year ago, tied for second among defensive tackles. And Jerry Hughes, after disappointing as the Colts' top pick in 2010, collected 10 sacks last season despite starting just one game.

Since this four-man unit was assembled for the 2013 season, the quartet has collected 77.5 sacks, 125 QB hits and 92 tackles for loss, and four games still remain in the season. Buffalo's defense finished with 57 sacks a year ago, second only to the Panthers' 60, and currently leads the league by six with 48 on the year.

"They just get after it," C.J. Anderson said Wednesday. "Their front four is really good and that's what makes them go."

Facing a talented front is nothing new for the Broncos' offense, which has dealt with the Chiefs (twice), Seahawks, Cardinals, Jets, 49ers, Rams and Dolphins this year, all of which feature top-flight edge rushers and/or disruptive penetrators on the interior. But the depth, talent and production of Buffalo's unit might bring the biggest challenge to date.

"We've played some pretty good teams but across the board, all four guys are legitimate Pro Bowl-caliber players," Virgil Green said Wednesday. "So up front is going to be a big test for us, but I believe we're ready for it."

Green's return from injury has been one of several factors that contributed to a ground game resurgence over the past two weeks. Last week, the fourth-year tight end handled Tamba Hali and Justin Houston on the edge despite giving away plenty of size in either matchup. Against the Bills, he could see plenty of Mario Williams, who brings a different challenge with more size.

"He's going to make sure you don't run that ball outside," Green said. "He can set that edge and he's 290. I'm about 240, 250 so there's a huge weight discrepancy there, but at the end of the day, I'm going into the game with a mindset that regardless of how big he is, I'm going to move him off the ball. Whether that happens on every play or not, I don't know, but that's my mindset and my goal for this game."

While the Bills' D-line stands out, the Broncos' own defensive front doesn't expect to be overshadowed on Sunday.

"We talked about it as a front: Their strength is their D-line and our D-line, we feel like we're being challenged this week," Terrance Knighton said Wednesday. "We want to outplay their D-line. If they get a sack, we want to get two. If they get a TFL, we want to get three.

"So it's going to come down to the trenches, whichever O-line and D-line play better, and when it comes down to playing football in December, going to the playoffs is about teams that can run the ball and play good defense and I think that's why we've been successful the past few weeks."