Mookie Betts said that the most difficult part of the quest to repeat as World Series champions is that you’ll get every team’s best shot in the regular season. That’s particularly true for a team like the Mariners, who are trying to prove that their strong start to the season is for real.

• Betts drilled by pitch, out Tuesday

Betts’ theory was evident Monday as the Dodgers fell behind early and weren’t able to string together enough hits to complete the comeback, dropping the series opener to the Mariners, 4-3, at T-Mobile Park. But their more immediate concern is for Betts after he was drilled in the right forearm by a Rafael Montero 96 mph fastball in the ninth inning.

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“It’s kind of a right forearm, a lot of soft tissue,” said Dodgers manager Dave Roberts. “I’m sure there’s going to be some bruising, maybe some swelling, so I just won’t know more until he shows up tomorrow.”

As the ball made contact with the forearm, Betts immediately went down in agony. He stayed down for about a minute while Roberts and a trainer checked on him. Betts eventually fist-bumped the trainer and ran down the first-base line. He stayed in the game, but was in clear pain. Corey Seager grounded out into a game-ending 4-6-3 double play two pitches later.

Roberts said he wasn’t sure what tests Betts was set to undergo. The Dodgers on Tueday announced that Betts would not be in the lineup for Tuesday’s game. The Dodgers are off on Wednesday before their four-game series against the Padres at Dodger Stadium begins Thursday.

“Obviously Mookie is going to want to be in there,” Roberts said Monday night before Betts' status was known. “I just want to make sure that it doesn’t affect his throwing or his swing, so I think that he’s pretty honest with me. So if he feels like he can play, then he’ll be in there.”

While the Dodgers are cautiously optimistic that it'll be a minimal absence for Betts, if any, losing their star outfielder would be yet another blow to a team that has dealt with their fair share of injuries through the first 17 games. Cody Bellinger, Gavin Lux and Tony Gonsolin -- all key contributors -- are currently on the injured list.

The team’s depth has been put to the test. They’re hoping they won’t have to figure out how to replace Betts.

“You never want to see that with anybody, especially up near the hands,” said Dodgers catcher Will Smith of Betts’ plunking. “Hopefully he’s all right. I’m sure he’s getting an X-ray and stuff like that, but I hope he’s fine.”

Losing Betts would also be a huge blow to a Dodgers lineup that is currently in a mini slump. The Dodgers have one of the best offenses in the Majors, so they’ve set a high bar for themselves with a strong performance to start the season. But recently, they’ve looked a bit more human.

Seager hit a two-run homer and Zach McKinstry added an RBI single on Monday, but Justus Sheffield and the Mariners’ bullpen were able to hold the Dodgers to just five hits. After their torrid start at the plate, the Dodgers have mustered just 11 hits and scored three runs over their last three games.

“Today, we just couldn’t put a bunch of hits together,” Roberts said. “We had the winning run on first base in the ninth inning. I thought we competed, like I would expect. Just got behind the eight-ball a little bit.”

The Dodgers’ best chance to tie the game came in the sixth inning when Smith laced a liner to third base. The ball had an expected batting average of .620, but Seattle third baseman Dylan Moore, who shifted from second base to third after Ty France left with an injury on a plunking eerily similar to Betts’, made a terrific diving catch to end the inning.

“I thought it might’ve had a chance to get over, and it probably would’ve tied the ballgame with Mookie at second,” Smith said. “But Moore made a really good play and kept them in the lead.”

It was the first time this season the Dodgers didn’t hold a lead in a game. It was also the first time the Dodgers lost back-to-back regular-season games since Sept. 10-12 last season against the D-backs and Astros.

But all eyes will be on Betts and his status moving forward.

“You just hope that it’s not bad,” Roberts said. “So, fortunately, I think the soft-tissue part of it is a good thing.”