But on the first play from scrimmage, Fields’ pass to Cordarrelle Patterson was batted into the air where it was intercepted by former Steelers outside linebacker Bud Dupree at the 34 for the game’s first turnover.

Elandon Roberts sacked Herbert on first down to push the Chargers back, and after a three-and-out, the Steelers got the ball back at their own 15.

The Steelers marched downfield with the help of three Los Angeles penalties – including personal fouls on safety Derwin James and Khalil Mack – to set up a 30-yard field goal by Boswell for a 13-10 lead with 14:14 remaining in the game.

“(We) played great for a long time. Played great on offense for a long time. Played great on defense for a long time,” said Chargers head coach Jim Harbaugh. “And then the drive with the three penalties, even that drive, they were able to hold to a field goal, 45 yards of penalties.”

Herbert and left tackle Rashawn Slater were both injured on the previous drive, Herbert aggravating an ankle injury that had forced him out of practice all week, Slater with a pectoral muscle injury. That forced backup Taylor Heinicke into the game for Los Angeles.

The Chargers moved the ball out to midfield, but T.J. Watt picked up a third-down sack, ending the threat and forcing Los Angeles to punt.

Taking over inside their own 20, the Steelers moved the ball out to midfield when Fields found Austin in the middle of the field by himself in the Chargers’ zone defense. Austin caught the ball, turned upfield and outraced safety Elijah Molden to the end zone to give the Steelers a 20-10 lead with 7:02 remaining in the game.

“They were just in the zone. Quartering, you’re really just high-lowing that hook defender,” said Fields. “The hook defender took (Pickens) underneath and Calvin was right behind him. Great play call.”

Herbig and Cam Heyward both recorded sacks on Los Angeles’ next possession, ending any chance the Chargers would have of a comeback.

The Steelers’ offense made that a moot point, running out the clock the rest of the way, with Najee Harris finishing things off with a run to the 1 at the two-minute warning.

The Steelers rushed for 114 yards, with Harris, despite a slow start, finishing with 70 yards on 18 carries.

“They just wanted to be the best defense on the field,” Tomlin said of his defense, which entered the game having allowed the second-fewest points (16) this season to Los Angeles (13).

“They respond to those things and take those challenges very personally, and they played like it.”