Denver Broncos seek major upset over Buffalo Bills

Why it matters: It's an enormous test for rookie quarterback Bo Nix, who will rely on the leadership of veteran head coach Sean Payton to orchestrate a colossal upset.

The big picture: The Bills (13-4) are heavily favored, playing at home — where they're undefeated this season — with star quarterback Josh Allen leading a franchise set to make its sixth consecutive playoff appearance.

• Buffalo, seeded second in the AFC, is a legitimate Super Bowl contender.

The intrigue: Payton's acumen in the offseason brought the right players to the cash-strapped Broncos after the disastrous Russell Wilson saga.

Zoom in: Denver (10-7) has its own rising star in Nix, whose emergence as a passing threat and leader has Broncos fans dreaming about lifting the Lombardi Trophy for a fourth time.

Context: The Broncos are arguably stronger when they don't have the ball, thanks to a defensive unit that led the regular season in sacks (63) and made consistently decisive plays.

• All eyes will be on cornerback Patrick Surtain II and linebacker Nick Bonitto, who are capable of turning games in their favor with a single play.

What's next: The game airs Sunday on CBS at 11am.