Chargers' defense melts down in heartbreaking loss to Steelers

Exhilarating win for Vick, Steelers on MNF (1:17)

Mike Tirico and Jon Gruden break down Michael Vick's performance on Monday Night Football to guide the Steelers past the Chargers. (1:17)

SAN DIEGO -- The San Diego Chargers owned a three-point lead with just under three minutes remaining after rookie kicker Josh Lambo drilled a 54-yard field goal.

But with five seconds left, Pittsburgh running back Le’Veon Bell took a direct snap and fought his way to the goal line for a touchdown and a 24-20 victory on Monday night. The score capped a 12-play, 80-yard drive by Steelers quarterback Mike Vick.

Bell's touchdown ruined an impressive return from a four-game suspension by Chargers tight end Antonio Gates.

Gates became the ninth player in NFL history to catch 100 career touchdown passes when he scored on a 12-yard pass from Philip Rivers with 9:50 left in the first quarter.

Gates had three catches on the opening drive that culminated in the touchdown. He added an 11-yard touchdown on a corner route with just more than eight minutes left in the game.

Gates now sits alone at No. 7 all time with 101 touchdowns.

Rivers now has 262 career touchdowns passes, moving past Dave Krieg for 13th in NFL history.

With the loss, the Chargers now are 2-3 and tied with the Oakland Raiders (2-3) for second place in the AFC West, three games behind the undefeated Denver Broncos (5-0). The Kansas City Chiefs, losers of four straight, are 1-4.

The Chargers dropped to 22-21 in Monday night games, and 32-28 in nationally televised night games.

What were they thinking? The Chargers once again struggled to run the football, a troubling trend after the team used a first-round selection on Melvin Gordon. San Diego finished with just 52 rushing yards.

One reason to panic: Rivers threw his fifth interception of the season, the third one returned for a score. Pittsburgh safety Antwon Blake intercepted a ball intended for Malcom Floyd and returned it 70 yards for a touchdown in the third quarter. Rivers now has 10 turnovers in his past 11 games.

Fantasy watch: While Gordon had just 42 rushing yards, he finished with seven catches for 52 yards for 94 total yards from scrimmage.

Ouch: The offensive line continues to deal with a rash of injuries. Starting left tackle King Dunlap (concussion) and left guard Orlando Franklin (ankle) did not play. Dunlap’s replacement, Chris Hairston, had to leave the game due to an ankle injury. The Chargers adjusted by moving right tackle Joe Barksdale to left tackle, moving left guard Kenny Wiggins to right tackle, and bringing in Chris Watt to play left guard. However, Watt suffered a head injury and had to leave the game. Watt was replaced at left guard by J.D. Walton.