Delhomme threw a 14-yard touchdown pass to tight end Dante Rosario as time expired to lift the Carolina Panthers to a shocking 26-24 win over the Chargers on Sunday.
It was a heart-stopping capper to a game that swung wildly with a big defensive play by each team in the second half.
After Philip Rivers rallied San Diego with his third TD pass of the game, Delhomme moved the Panthers to the San Diego 14-yard line with 2 seconds left before calling his final timeout.
Delhomme dropped back on fourth down, scrambled and then found Rosario in the back of the end zone to give Carolina a 25-24 lead. Carolina coach John Fox raised his arms and clenched his fists as the offensive players mobbed each other between the goal posts and the stands.
John Kasay, who had four field goals, added the extra point to set the final score.
Delhomme returned after missing all but three games last season with an elbow injury that required reconstructive surgery.
He was 8-of-11 for 68 yards on the final drive and finished the afternoon 23-of-41 for 247 yards.
The Chargers, picked by many to reach the Super Bowl, seemed to have this one wrapped up after Rivers threw a 5-yard scoring pass to Vincent Jackson with 2:27 left.
That came six plays after first-round draft pick Antoine Cason slammed receiver D.J. Hackett to the turf after a catch, forcing the ball to pop out. Outside linebacker Shaun Phillips recovered at the Carolina 28 with 4:56 to play.
Carolina's big defensive play came late in the third quarter, with San Diego leading 10-9.
Pro Bowl tight end Antonio Gates caught a pass from Rivers that would have given San Diego a first down at the 31. But safety Chris Harris ripped the ball out of Gates' hands as he was going down. The ball popped straight to cornerback Chris Gamble, who ran it into the end zone.
Chargers coach Norv Turner challenged, but the play was upheld, costing San Diego a timeout. Carolina coach John Fox chose to go for an extra point by Kasay rather than a 2-point conversion, and the Panthers led 16-10.
After a punt by San Diego's Mike Scifres went only 32 yards, the Panthers jumped ahead 19-10 on a Kasay's fourth field goal, from 49 yards.
The Chargers came right back with Gates catching a 24-yard touchdown pass from Rivers to pull to 19-17 with 6:45 to play. Rivers rolled left and threw across his body to Gates, who beat linebacker Na'il Diggs for the score.
San Diego made it to the AFC championship game last season, losing 21-12 at New England as Rivers played the whole game on a shredded anterior cruciate ligament in his right knee that required surgery.
The Panthers are coming off a 7-9 season. They played without leading receiver Steve Smith, suspended by the team for two games for sucker-punching Ken Lucas in practice on Aug. 1, breaking the cornerback's nose.