LOS ANGELES — Third baseman Max Muncy was diagnosed with a Grade 1 oblique strain and landed on the injured list Friday, a major blow to a Los Angeles Dodgers team that finds itself fading in the standings.

Muncy was originally a late scratch from Wednesday’s lineup after feeling soreness in his right side during pregame batting practice. The Dodgers’ hope was that sitting out for the finale from Angel Stadium, then getting extra rest during the Thursday off day, would allow Muncy to return for a critical series against the division-rival San Diego Padres, who have taken a one-game lead in the National League West.

But Muncy will miss this weekend’s series from Dodger Stadium, as well as the following series from San Diego’s Petco Park next weekend.

“I don’t think anyone expects it to be season-ending,” Dodgers manager Dave Roberts said, “but hopefully it’s sooner than later.”

Roberts doesn’t believe the current oblique injury is as bad as the one that forced Muncy to miss about two months last year, but even in a best-case scenario, the Dodgers might be without their third baseman and left-handed power hitter until around mid-September.

Muncy got off to a bad start this year before turning it on in the middle of May, slashing .312/.438/.616 with 11 home runs in a stretch of 41 games. Muncy then injured his left knee during a scary collision at third base and wound up missing most of July. He returned Aug. 4, went 8-for-23 with four home runs over the course of eight games, and now he’s out again — at a time when the reigning World Series champs could really use some reinforcements.

The Dodgers held a nine-game lead in the NL West as of July 3 and have since gone 12-21 to fall a game back of a surging Padres team that arrived in L.A. on the heels of a five-game winning streak. As many as six high-leverage relievers reside on the Dodgers’ IL, though three of them — Michael Kopech, Kirby Yates and Tanner Scott — are nearing returns. The offense, meanwhile, has been mostly unproductive over the past six weeks, posting an 0.708 OPS that ranks 22nd in the major leagues.

During Muncy’s absence, the Dodgers will use Alex Freeland, a switch-hitting rookie who’s batting .176 in his first 12 games, and Buddy Kennedy, a right-handed-hitting journeyman with a career .193 batting average. Other potential reinforcements like Tommy Edman, Hyeseong Kim and Enrique Hernandez remain on the IL and aren’t close enough to a return.

“It’s certainly a tough loss,” Roberts said. “I think it’s just guys got to continue to perform to their abilities. It’s hard to kind of backfill Max, what he means, as far as the plate discipline, the slug, the on-base, all that stuff. I feel good about our lineup, the guys that we have, and they just have to go out there and take good at-bats. That’s all we can do right now.”