San Diego Chargers safety Clinton Hart had a rough final few minutes against the Kansas City Chiefs. He was flagged for pass interference against Tony Gonzalez, setting up a touchdown past Hart to Gonzalez. But Hart redeemed himself by breaking up a two-point conversion pass attempt (shown in this photo) that preserved the Chargers' 20-19 victory Sunday in San Diego.

San Diego ? This wasn’t about changing defensive coordinators in midseason. It was about making a play that quite possibly saved the San Diego Chargers’ season.

Burned by a pass-interference call and then a touchdown catch by star tight end Tony Gonzalez, strong safety Clinton Hart swatted away Tyler Thigpen’s two-point conversion pass intended for Gonzalez with 23 seconds left to preserve the Chargers’ 20-19 victory over the lowly but scrappy Kansas City Chiefs on Sunday.

“As the call happened, I said to myself, I wasn’t going to let him score this two-point conversion,” Hart said.

“We knew they were going for the win. Denver did it, and I guess they figured they could do it. But surprise, surprise, we stood up and made a difference,” Hart said.

Coincidentally, San Diego lost to Denver 39-38 in Week 2 when the Broncos made a last-minute two-point conversion.

San Diego’s defense played so erratically in the season’s first half that defensive coordinator Ted Cottrell was fired and replaced by inside linebackers coach Ron Rivera.

Despite coming off their bye, the Chargers (4-5) looked lethargic in the first half and were booed heading to the locker room trailing 13-6.

Philip Rivers rallied them with two touchdown passes late in the game, then Hart saved them.

Thigpen moved the Chiefs (1-8) to the Chargers 18 with 41 seconds left. On a second-down pass, Hart came from the side to knock a pass away from Gonzalez and was called for a questionable pass interference penalty that gave the Chiefs a first-and-goal at the one. After an incomplete pass and a two-yard loss by fullback Mike Cox, Gonzalez caught a three-yard touchdown pass to pull the Chiefs within one. Hart and nickel back Antoine Cason were covering Gonzalez tightly.

Then came the big play. Hart deflected Thigpen’s pass right to Quentin Jammer, who made the interception while on the ground.

“I got into him really good,” Hart said. “I pressed him. He gets his big body and tries to push you off, and he tried to push me off. I latched onto the inside of his pads and I said, ‘I’m not going to let you push me off.’ And I kind of got underneath him, got the ball down. Jammer got a pick.”

Gonzalez thought there should have been a flag.

“It was ridiculous, he held me,” the tight end said.

Hart disagreed.

“If he pushes me off, they’re not going to call it,” Hart said. “I said to myself, ‘I’m not going to let him push me off because if I’m holding my ground, I’ve got a right to my spot.’ That’s what I did. I held my ground.”

Gonzalez had 10 catches for 113 yards and two touchdowns.

Playing his fourth game, Thigpen was 27-of-41 for 266 yards and three touchdowns.