Here are three keys to watch from the Dolphins' perspective:
No. 1: Can Miami's secondary hold up?
The Dolphins' defense is limping into the playoffs, particularly on the back end with their secondary. Their two starting safeties from Week 1 (Reshad Jones, Isa Abdul-Quddus) are on injured reserve, and No. 1 cornerback Byron Maxwell is doubtful for Sunday's playoff game with an ankle injury. Even replacement safety Bacarri Rambo is ailing with a chest injury. Defensive coordinator Vance Joseph must get by with a patchwork group, and that will be tough against Pittsburgh's dynamic receiving weapons led by Pro Bowler Antonio Brown.
No. 2: Will RB Jay Ajayi run wild again?
Ajayi's 204 rushing yards against the Steelers in Week 6 was a springboard to his breakout season. Sunday will mark a full-circle moment for Ajayi to face the same defense in the playoffs. Expect revenge to be on the mind of Pittsburgh's defense to prove Ajayi's first performance was a fluke. A dominant rushing attack with Ajayi is Miami's best chance to control the game and pull the upset -- and both sides know it.
No. 3: The Matt Moore factor
Ryan Tannehill played well against Pittsburgh in Miami's initial meeting. But due to a knee injury, the Dolphins are starting Moore in the playoffs. Moore is 2-1 as a starter this season and has given Miami's passing game a more aggressive look. He's thrown eight touchdowns in three games. On the downside, Moore's aggressiveness has led to an interception in all three starts. He must remain aggressive but avoid costly turnovers on the road in the postseason.