Ben Roethlisberger and the Steelers’ new-look offense overcame a slow start, Ulysees Gilbert returned a blocked punt 9 yards for a touchdown and Pittsburgh rallied to a season-opening 23-16 win over the Buffalo Bills on Sunday.

Down 10-0, the Steelers scored on each of their first four possessions of the second half, with Roethlisberger putting Pittsburgh ahead for good by lobbing a 5-yard touchdown pass to Dionte Johnson in the left corner of the end zone.

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The pass initially went off Johnson’s fingertips, but the receiver was able to secure the ball before tumbling out of bounds 3:41 into the fourth quarter. The Steelers then extended their lead to 20-10 some 90 seconds later with Miles Killebrew bursting up the middle to block Matt Haack’s punt, with Gilbert scooping up the loose ball and running it in untouched.

In opening his 18th — and perhaps final — season, Roethlisberger posted his 36th career fourth-quarter comeback to tie Drew Brees for third on the NFL list. He finished 18 of 32 for 188 yards and a touchdown.

Chris Boswell hit all three field-goal attempts, including a game-sealing 45-yarder with 2:42 remaining.

The Steelers defeated the Bills after losing to them in each of the past two seasons — both times in primetime.

In a matchup of defending AFC division champs, the Bills produced a dud following an offseason in which many pegged them as Super Bowl contenders.

Buffalo’s Allen-led dynamic offense sputtered in resembling nothing of the aggressive unit which set numerous scoring and passing records last year. Allen finished 30 of 51 for 270 yards with a 3-yard touchdown pass to Gabriel Davis.

The Bills otherwise settled for Tyler Bass hitting three field goals and, worse still, failed to convert consecutive fourth-down opportunities to open the second half.

Give the Steelers defense credit for keeping them in the game.

Gilbert’s touchdown came when the Bills were forced to punt following a three-and-out in which James Pierre punched the ball out of the arms of Emmanuel Sanders to prevent a 20-yard catch on second down, and T.J. Watt followed by sacking Allen for a 6-yard loss.

Watt certainly made his presence felt three days after becoming the NFL’s top-paid defensive player by signing a four-year, $112 million contract extension. He sacked Allen in the second quarter and forced a fumble by chasing the quarterback down from behind on third-and-13 at the Pittsburgh 41.

Roethlisberger overcame a slow start under Steelers new offensive coordinator Matt Canada. Pittsburgh combined for just three first downs and 54 net yards on its six possessions in the first half. Rookie first-round draft pick, running back Najee Harris, had 7 yards on eight carries in the first half, and finished with 45 yards on 16 carries.

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BIG OPENING

The Bills scored on their opening possession with Bass hitting a 37-yard field goal, which was set up by Isaiah McKenzie’s 75-yard kickoff return.

Buffalo didn’t score again until its final possession of the half, in which Allen capped a 13-play, 91-yard drive with a 3-yard touchdown pass to Davis. Facing third-and-goal, Allen threaded a perfect pass in hitting Davis in stride, and a step ahead of defender Cameron Sutton.

WATT’S UP

Watt got his 18th career forced fumble, which is the most in the NFL since he was drafted in 2017. Watt also upped his sack total to 51 1/2.

FOR THE BLOCK

Killebrew’s blocked punt was Pittsburgh’s first since Roosevelt Nix against Atlanta in 2018. Gilbert’s TD return off a blocked punt was Pittsburgh’s first since Bills current special teamer Tyler Matakevich scored against Cleveland in 2017.

UP NEXT

Steelers: Home opener against Las Vegas Raiders on Sept. 19.

Bills: At Miami Dolphins on Sept. 19.