Geno Smith

Ladies and gentlemen, the victorious Justin Herbert.

Give him a hand.

(The Chargers wish you could.)

Herbert, who has been knocked around all season but so far had avoided injury, saw that streak come to a disappointing end Sunday, even though the Chargers walked away with a 31-14 win over the Las Vegas Raiders. It was the Chargers’ most lopsided victory in the rivalry since 2008.

The spiral-slinging star quarterback sustained a broken bone in his left (non-throwing) hand that will require him to undergo a medical procedure on Monday, coach Jim Harbaugh said. Harbaugh said he didn’t know if Herbert will miss time because of the injury, but Herbert told reporters he’s approaching the week as if he will play in the Chargers’ next game against the Philadelphia Eagles on Dec. 8.

Herbert only missed part of one series against the Raiders and would lead his team to an AFC West win, but he was limited.

He had to operate out of shotgun, as opposed to being under center, wasn’t as sharp and accurate as he typically is, and protected a gloved left hand that looked borrowed from a Macy’s mannequin. He was still better than most NFL quarterbacks, though, even with one hand essentially tied behind his back. He completed 15 of 20 passes for 151 yards, with two touchdowns and an interception.

Herbert’s injury is an ominous sign for a franchise facing a brutally difficult finish to the regular season with remaining games against Philadelphia, Kansas City, Dallas, Houston and Denver. The Chargers need to win at least two of those for a realistic chance of making the postseason.

Sunday, the teams were tied 7-7 at halftime. The Chargers (8-4) scored with a 10-yard touchdown reception by Quentin Johnston on the opening possession, and the Raiders answered in the second quarter with a six-yard touchdown catch by Brock Bowers.

Raiders quarterback Geno Smith was intercepted once in the half by Tony Jefferson, who made an acrobatic snare of a tipped pass on the sideline, and the visitors answered by picking off Herbert in the end zone.

Chargers running back Kimani Vidal broke that tie in the third quarter with a 59-yard touchdown run, and his team would widen that lead with a seven-yard touchdown reception by Ladd McConkey late in the quarter. Vidal finished with 126 yards in 25 carries and McConkey led the Chargers’ receivers with 39 yards on four catches.

Fans cheer as Chargers running back Kimani Vidal scores on a 59-yard touchdown run in the third quarter Sunday at SoFi Stadium.

(Robert Gauthier / Los Angeles Times)

The Chargers’ defense put the clamps on the Raiders (2-10), limiting them to 31yards rushing and one first down on the ground. Las Vegas has gone a franchise-record seven consecutive games with less than 75 yards rushing — a stat made worse by the fact the Raiders used the sixth overall pick last spring on running back Ashton Jeanty.

Smith was sacked four times and threw for 125 yards on 18-of-23 passing.

The Raiders did have a spectacular highlight, a one-handed, ankle-high touchdown catch by a falling Bowers in the fourth quarter. It was his second touchdown catch in three plays, as the first was nullified because Harbaugh had called timeout an instant before the snap.

Herbert sustained the injury with about five minutes remaining in the opening quarter when he stepped up in the pocket, scrambled to his left and gained a yard before being tackled by safety Jeremy Chinn. The quarterback’s left hand collided with the defender’s helmet.

Although Herbert popped to his feet and threw a touchdown pass on the next play, TV replays would later zoom in on his hand as he made his way to the sideline and the tip of his finger appeared to be bent in an unnatural way.

Chargers quarterback Justin Herbert is sacked by Raiders defensive end Maxx Crosby in the third quarter Sunday.

(Robert Gauthier / Los Angeles Times)

Beating the Raiders was non-negotiable. Las Vegas had come into the game having lost nine of its last 10 games, and fresh off a two-touchdown home loss to Cleveland in which Smith was sacked 10 times.

It has been a woeful year for first-year Raiders coach Pete Carroll, who last week bid farewell to offensive coordinator Chip Kelly. Greg Olson replaced him as interim playcaller and was similarly unsuccessful. What happens in Vegas stays in Vegas — or so prays the rest of the league.

So dispirited are Raiders fans that a game that’s typically a silver-and-black takeover of SoFi Stadium was far closer to 50/50.

The Chargers, meanwhile, have struggled to recapture the magic of September when they opened the season with three consecutive division victories. Injuries have made that a fantasy, as they have gone 5-4 since including blowout losses to Washington, Indianapolis and Jacksonville.