LAS VEGAS -- Chargers linebacker Daiyan Henley, battling fever and an illness, set the tone on the game's first play from scrimmage by intercepting Raiders quarterback Geno Smith.

Henley went on to have a big performance -- as did the rest of the Los Angeles defense.

They shut down the Raiders, Justin Herbert passed for 242 yards and two touchdowns and the Chargers went on to a 20-9 victory Monday night to give Los Angeles coach Jim Harbaugh a win over rival Las Vegas coach Pete Carroll.

The Chargers, however, lost defensive end Khalil Mack to a left elbow injury late in the first quarter. He went to the locker room, but returned with his arm in a sling. Harbaugh said Mack will need to undergo imaging tests.

Herbert also led the Chargers in rushing with 31 yards. His two TD passes went to Quentin Johnson and Keenan Allen, who returned to the Chargers on a one-year contract after playing last season in Chicago.

It was Los Angeles' defense that suffocated the Raiders, holding them to 218 yards, beginning with Henley's interception.

"It definitely set the tone," Henley said. "One thing we've been preaching with our defense is to start fast. We know it's a long game and we have three more quarters to go. We just wanted to make sure we finished strong as well."

Henley recorded 10 tackles that included two for loss and a sack. He also broke up two passes.

"He's a true competitor," Herbert said. "We know how bad he's feeling. For him to show up and give us his best effort like that, he's a true leader on the team."

For the Raiders (1-1), Smith threw three interceptions while completing 24 of 43 passes for 180 yards.

"Geno is a 70% guy, and he wasn't that tonight," Carroll said. "And more so because of the attempts that we made. I thought they took away from that (with deep pass coverage), and we just got to take what's given to us. I'm not sure that that's the case until I see the film, but I bet that's what it is."

Ashton Jeanty, taken sixth in this year's draft, gained 43 yards on 11 carries and has 81 yards through two games.

This win puts the Chargers (2-0), who open this season with three consecutive games against divisional opponents, atop an AFC West that has belonged to Kansas City since 2016. Los Angeles is making an early claim on a division in which the Chiefs are off to an 0-2 start.

Harbaugh has at least temporary bragging rights over Carroll in their first meeting since Dec. 14, 2014. Their combative history as opposing coaches dates to 2007 when Harbaugh was at Stanford and Carroll at Southern California. They later became NFC West rivals, Harbaugh in San Francisco and Carroll in Seattle.

"It was a battle like all the ones you play the Raiders and a Pete Carroll team," Harbaugh said. "Both teams were just fighting. Everybody was all in out there. There was nobody that was just right down the middle."

Carroll, who turned 74 on Monday, had some help with Raiders minority owner -- and Fox Sports NFL analyst -- Tom Brady in the coaches' booth wearing a headset. Brady was in Las Vegas also to promote a flag football tournament next year in Saudi Arabia.

The Chargers took a 20-6 lead midway through the third quarter and then forced the Raiders to eat clock. Las Vegas took 11:15 to go 62 yards on 19 plays before settling for a field goal.

But then Los Angeles perhaps got too cute, trying an end run on a fourth-and-1 at its 44-yard line that resulted in a fumble. But Smith threw his third interception shortly afterward, and that was it for the Raiders' last realistic threat.

Raiders linebacker Devin White joined New Orleans' Demario Davis as the only players with at least 600 tackles and 20 sacks since 2019.

Terence Crawford defeated Canelo Alvarez on Saturday night at Allegiant Stadium to become the unified super middleweight champion. Crawford remained in Las Vegas and attended this game, though he admitted in an ESPN interview during the game that he's a Green Bay fan.

Chargers: Host the Denver Broncos on Sunday.

Raiders: Visit the Washington Commanders on Sunday.

Herbert and strong defense lead Chargers to 20-9 win over Raiders