SAN DIEGO -- When Le'Veon Bell is on your side, the decision is easy.

"We have to run the football," Pittsburgh Steelers coach Mike Tomlin said. "We have Le'Veon Bell."

Bell's 1-yard scoring run with no time remaining lifted the Steelers past the San Diego Chargers 24-20 Monday night.

The Chargers grabbed the lead on rookie Josh Lambo's 54-yard field goal with 2:56 to play. The Steelers then drove 80 yards in 12 plays for the win.

On first-and-goal at the San Diego 1-yard line with five seconds remaining, Bell took a direct snap and ran to the left side. The running back was wrapped up by linebacker Donald Butler, but Bell was able to stretch the ball over the goal line for the win.

"It was definitely the most meaningful for sure," Bell said of where his touchdown ranks. "To win the game, the game-winner on the last play of the game, that's what you dream about it."

Quarterback Philip Rivers said it was a nightmare for the Chargers. Not only the result, but the surroundings as well. Chargers fans had a tough time matching the chants from the Steelers boosters.

"It was a tough environment tonight," Rivers said of the thousands of Steelers fans. "It was like being on the road."

Tomlin said he never hesitated in going for the win instead of kicking the tying field goal.

"It was time to go to the mattresses, if you will," Tomlin said. "We had to do what was required to win. Le'Veon gave us an opportunity to win, and we were trying to do everything we could to move the football."

Chargers tight end Antonio Gates returned from a four-game suspension and caught two touchdown passes. He finished with nine receptions for a game-high 92 yards.

"It was great to have him back," Rivers said. "He was rolling. He was a big contributor."

Rivers completed 35 of 48 passes for 356 yards with two touchdown passes and one interception.

Pittsburgh quarterback Michael Vick was 13 of 26 for 203 yards with a touchdown and an interception.

Bell rushed for 111 yards on 21 carries.

San Diego (2-3) scored the first 10 points of the fourth quarter to take a 17-10 lead, but Pittsburgh (3-2) wasn't down long, tying the game one play after the Chargers went ahead. Vick hit wide receiver Markus Wheaton for a 72-yard touchdown, with Wheaton burning cornerback Brandon Flowers on a stop-and-go route.

The Chargers seized a seven-point lead with eight minutes to play on Gates' second touchdown reception. This one covered 11 yards as Gates slipped past safety Mike Mitchell and beat safety Robert Golden to the corner of the end zone with an over-the-shoulder catch of Rivers' pass.

Lambo's 40-yard field goal tied the game at 10-all to open the fourth quarter.

Late in the third quarter, Pittsburgh cornerback Antwon Blake picked off Rivers' pass and returned it 70 yards for a touchdown. That gave the Steelers their first lead, 10-7.

Rivers was trying to connect with wide receiver Malcom Floyd on a crossing route, which Floyd broke off. Blake weaved through the Chargers en route to the end zone, with Rivers giving one last dive at him near the goal line as he went in standing up.

It was Rivers' fifth interception of the season and gave him a turnover in 10 of his last 11 games. It was also Rivers' third pick returned for a touchdown this season.

"I always take the blame for interceptions," Rivers said. "It leaves my hand. I'm the only one that threw it."

The Steelers reached the San Diego 38 in the closing two minutes of the half, but the drive stalled when Vick was sacked by defensive end Corey Liuget.

Pittsburgh turned to Bell -- 36 rushing yards on the drive -- midway through the second quarter to get on the scoreboard.

Kicker Chris Boswell's 37-yard field goal pulled the Steelers to within 7-3.

The Steelers reached Chargers territory late in the first quarter, thanks to a 39-yard reception by wide receiver Antonio Brown from Vick. However, cornerback Jason Verrett made a nice play in single coverage when he deflected a pass intended for Brown on third-and-8 at the San Diego 41. That forced the Steelers to punt.

The Chargers struck quickly and Rivers was determined to get Gates involved, hitting him with his first pass.

Gates later had a 12-yard scoring reception, giving the Chargers a 7-0 lead five minutes into the game. It was Gates' 100th career touchdown, as he joined Tony Gonzalez as the only tight ends with 100 touchdowns.

The drive's key play was running back Danny Woodhead delivering 31 yards on a catch. That and 15 yards that were added for a personal foul, enabled the Chargers to reach the 6.

Bell rushed for 89 yards on 14 carries in the first half, but it was his final yard that he will long remember. Same goes with the Chargers.

"They made one more play," San Diego coach Mike McCoy said. "He's a special back and a great player, and we knew what we were dealing with."

NOTES: Chargers LT King Dunlap (concussion) and LG Orlando Franklin (ankle) were unable to start. ... Chargers QB Philip Rivers set a franchise record with his 149th consecutive start. ... San Diego SS Jahleel Addae returned after missing three games with an ankle injury. ... Steelers WR Martavis Bryant was inactive after serving a four-game suspension. ... Pittsburgh TE Heath Miller caught a pass in his 102nd consecutive game. ... Steelers QB Michael Vick was headed to San Diego as the 2001 top pick before the Chargers traded down in a deal that secured them RB LaDainian Tomlinson.