PITTSBURGH -- Once leading by two possessions, the Pittsburgh Steelers needed a fourth-down sack from Terrell Edmunds to escape a major collapse in their Heinz Field debut Sunday afternoon. The Steelers held a five-point lead when Edmunds' 11-yard sack sealed a 26-21 victory over the Denver Broncos.

The Steelers' lead shrunk to five points by late in the fourth quarter as they amassed costly penalties -- including six that resulted in Broncos first downs. They finished with 10 penalties for 89 yards.

After a three-and-out drive, the Steelers gave the ball back to the Broncos with 6:15 to go. Aided by a third-down pass interference call against Edmunds, the Broncos bled the clock. The Steelers offense, thought to be cured with the return of quarterback Ben Roethlisberger, disintegrated in the second half.

The opening drive of the third quarter ended with a bad Roethlisberger pick when Justin Simmons leapt up to snag a ball intended for JuJu Smith-Schuster on a cross-field third-down throw. The next series started out with a drop by James Washington and ended with a failed fourth-down conversion on the edge of field goal range as Roethlisberger's pass sailed over the head of tight end Eric Ebron.

Before Edmunds' sack, no play was more impactful than Bud Dupree's takedown of quarterback Drew Lock in the first quarter. Dupree caught Lock as he was stumbling away from T.J. Watt's shoestring tackle, causing the Broncos' quarterback to trip. Dupree slammed into Lock, knocking the ball free and setting up Mike Hilton to recover the fumble. Lock did not return to the game.

The Steelers had seven sacks overall, led by Watt's 2.5.

Silver lining: Mike Hilton. The do-everything DB had a massive game, recording eight tackles, two sacks, two quarterback hits and one fumble recovery.

Hilton was all over the field, bringing the energy to an otherwise energy-sapped stadium.

Pivotal play: Vintage Roethlisberger returns. Early in the fourth quarter, Roethlisberger rolled to his right and found an open field in front of him with ample space to pick up a first down. Instead of running, though, Roethlisberger fired a bullet to the end zone.

That was the right call, it turns out, because second-year receiver Diontae Johnson came down with the 28-yard touchdown pass, giving the Steelers a little room to breathe with a 10-point lead.

Although there were flashes of the Roethlisberger of old, the 38-year-old quarterback showed a few troubling moments, such as when he threw a third-quarter interception.

Roethlisberger completed 29 of 41 passes for 311 yards and was sacked once. He had two touchdown passes and one interception.

Pivotal play II: TJ and JJ Watt aren't the only Watt brothers who can bring the boom.

Derek Watt made a huge special-teams tackle as the Broncos punter Sam Martin attempted to kick the ball out of the end zone. Martin fumbled the snap and the Steelers' special teams collapsed on him with Watt making a big tackle for the safety. The score, the Steelers' last of the afternoon, gave the home team a 26-14 lead with 10 minutes to go.

Pivotal Play III: Welcome to the NFL, Chase Claypool. Claypool, a Notre Dame product, caught a deep pass from Roethlisberger in stride along the Broncos' sideline at about the 45-yard line and outran the Broncos' secondary to the end zone for an 84-yard touchdown -- his first in the NFL.

The score was the only play of the Steelers drive that started at their own 16-yard-line after a would-be 81-yard punt return touchdown by Diontae Johnson was wiped off the board because of a block in the back penalty.

Claypool caught all three of his targets Sunday afternoon for 88 yards along with the score.