The Rams' Marc Bulger, starting for perhaps the final time before the return of injured quarterback Kurt Warner, completed 36 of 48 passes for 453 yards and four touchdowns. Warner's career high in a single game has been 441 yards.
"Statistics don't mean too much," said Bulger, who was West Virginia's all-time passing leader. "When it mattered, the guys did not give up and Isaac Bruce made play-after-play."
"The way Marc was throwing the ball, I was saying to the coaches 'I'm not so sure that we just shouldn't throw this ball every snap,'" Rams coach Mike Martz said.
Warner hopes to return to action next week when the Rams host Chicago in a Monday night game.
"Going back to the bench will be fine. If this is it, this is it," Bulger said. "If I have one more week, I have one more week. Our whole team is so unselfish. I'm not going to be the guy that switches it. This is Kurt's team. When Kurt is ready, I am ready to sit. I have no problems with that."
Trying to become the first team to start 0-5 and still make the playoffs, the Rams (4-5) won their fourth straight under Bulger. He began the year as the Rams' third-string quarterback.
Bruce scored three times with one of them being a one-handed grab of a 34-yard pass with 3:06 left in the fourth quarter that brought the Rams within 24-21. He then gave St. Louis the victory with a sliding, seven-yard scoring reception.
Bruce's winning touchdown came after Dre' Bly recovered an onside kick at the St. Louis 46. Bruce had 10 catches for 163 yards.
The loss was the second in a row for the Chargers (6-3), who squandered a 10-point fourth-quarter lead.
San Diego's defense forced four turnovers and scored a pair of touchdowns on fumble returns of five yards by cornerback Ryan McNeil and 82 yards by linebacker Donnie Edwards.
The Rams totaled 524 yards, but fumbled the ball away four times. None of the turnovers was by Bulger, but two were by Bruce after making receptions.
St. Louis staged its comeback without star running back Marshall Faulk, who left with an injured left ankle during the fourth quarter. He was held to 36 yards on 13 carries and had a costly fumble at the San Diego three late in the first half. In St. Louis' three previous wins, Faulk rushed for 519 yards.
With the Rams trailing 24-14, Bulger did not have Faulk to lean on when the Rams took over on their own six with under five minutes left. But Bulger maintained his composure, completing four of five passes for 55 yards, including a 23-yarder to Bruce.
On second and four at the San Diego 34, Bulger lofted a pass down the right sideline for Bruce, who made a spectacular, one-handed catch over rookie cornerback Quentin Jammer at the San Diego five and raced into the end zone to pull the Rams within 24-21 with 3:06 left.
"I throw one up and throw a jump ball and he (Bruce) goes up with one hand and reels it in," Bulger said.
Since Martz had already used all of his timeouts, he decided to try an onside kick to get the ball back. The strategy worked as Jeff Wilkins bounced a kick high off the turf which was grabbed by a leaping Bly at the San Diego 46.
"I told Wilkey to put the ball as high as he can and I'd get the ball," Bly said. I'm just a very confident individual when it comes to getting the ball. Once we got the kick, I just knew we were going to punch it in."
"The percentages of them getting it is pretty slim, but the guy made a great kick and they just came up with the football," said San Diego's Twim Dwight.
Rookie Lamar Gordon, who was filling in for Faulk, caught three passes for 20 yards and broke off a nine-yard run to the San Diego 35, offsetting two false start penalties.
Following the two-minute warning, Bulger hit Holt with an 11-yard pass. Holt finished with seven catches for 118 yards. After spiking the ball to stop the clock, Bulger connected with Bruce on a 17-yard pass to the San Diego seven.
Two plays later, Bruce made a diving catch near the right sideline and just made it into the end zone, giving the Rams the lead with 1:14 left.
Ronney Jenkins returned the ensuing kickoff 52 yards to the St. Louis 46. Facing a fourth and 12, Drew Brees hit rookie Reche Caldwell with an 18-yard pass to the 30 with 25 seconds remaining.
Two plays later, cornerback Dexter McCleon intercepted a pass intended for Caldwell in the end zone to seal the win.
"I guess it's kind of shocking the way it ended for us," said Brees, who was 12 of 20 for 139 yards with two interceptions. "I think anytime you look at the percentages when your defense scores two touchdowns, I think the chances of the other team winning are probably five percent. So, this is a game that is that five percent."
San Diego's LaDainian Tomlinson rushed for 120 yards and a touchdown on 24 carries and took over the NFL rushing lead from Priest Holmes. Tomlinson has rushed for 965 yards, 57 more than Holmes.
"We didn't play all 60 minutes," Tomlinson said. "We got away with three-and-a-half quarters and we didn't finish the game. That's the bottom line. They played better than we did in the fourth quarter and they wanted it better than we wanted it."