Dolphins (10-6) at Steelers (11-5)

1:05 p.m. Sunday. Line: Steelers by 10

On Oct. 16, the Dolphins were 1-4, worst in the A.F.C. East. The Steelers were 4-1, kings of the A.F.C. North. They met in Miami, and the Dolphins won, in a game no one considered a postseason preview. But here they both are, together again in a playoff showdown.

The Dolphins won Round 1 because running back Jay Ajayi gained 204 yards on 25 carries and scored two touchdowns. It helped that Miami quarterback Ryan Tannehill completed 24 of 32 passes for 252 yards, but he has been out with a sprained knee since Week 11. It is up to Tannehill’s replacement, Matt Moore, who is making the first postseason start of his nine-year career, to provide air cover for the running game.

Steelers running back Le’Veon Bell missed the past two postseasons with knee injuries. Now, his ligaments are as healthy as his numbers. Bell rushed 110 times in the last four games of the regular season, for 569 yards, and he averaged 187 yards from scrimmage. Pittsburgh quarterback Ben Roethlisberger, who played with an injured knee in the first meeting with the Dolphins, has led the Steelers to seven consecutive victories.

Defense tips the scoreboard in Pittsburgh’s favor. This season’s team is not the Steel Curtain of old, but it pinches up inside the 20-yard line — with the N.F.L.’s fourth-ranked red-zone defense. Pick: Steelers