CLEVELAND -- A Monday examination in Boston on Triston Casas revealed what the Red Sox feared over the weekend in Pittsburgh.

The first baseman has a left rib fracture and isn’t going to be back in the lineup any time soon.

“He has a fracture so he’ll be out for a while,” Red Sox manager Alex Cora said prior to Tuesday’s opener of a three-game series in Cleveland. “Obviously, we had a pretty good idea a few days ago, but after all the tests in Boston, that’s what came out. We just have to be patient now. Timetable? There’s none.”

Cora said the club remains hopeful Casas will contribute again in ‘24, but wasn’t able to give even a ballpark figure on when that could be.

“This has to heal on its own. We’ve just got to be patient,” Cora said.

Casas suffered the injury taking a swing on a foul ball on Saturday in Pittsburgh. The club placed him on the 10-day injured list on Sunday.

Injuries to key players have become an unfortunate early-season trend for the Red Sox, who have done a nice job weathering it so far, taking a 13-10 record into this series against the Guardians.

At this point, Bobby Dalbec is going to get the majority of starts at first base. Dalbec has one hit in his last 42 at-bats with 27 strikeouts dating back to Sept. 27, 2023, and is off to a 1-for-30 start this season.

But Cora takes some stock in the fact Dalbec had a productive rookie season in ‘21, belting 25 homers to go with a .792 OPS in 417 at-bats.

An external acquisition shouldn’t be ruled out either.

“We’ve got Bobby now. He's my first baseman. He’ll play,” said Cora. “We’re going to play him a lot. Obviously, I bet the front office is studying the situation and looking around and seeing if we go somewhere else for that.

“I talked to Bobby today. He's done it before. He did it in ‘21. He was really good for us. He hit the ball out of the ballpark, played good defense. That’s something I told him. I said, ‘Hey man, just don't feel like one at-bat is going to dictate what we do with you now. Just go out there, have fun and play and put good swings on the ball and see what happens.”’

What’s happened to the Red Sox is that injuries have piled up since Spring Training.

Lucas Giolito, the team’s biggest acquisition of the offseason, tore his right UCL in his second Spring Training start and won’t pitch until next season.

Invaluable shortstop Trevor Story fractured his left shoulder trying to make diving play in Anaheim in the eighth game of the season, and is also out until ‘25.

Vaughn Grissom, acquired from the Braves for Chris Sale to become the team’s primary second baseman, hasn’t played a game for his new team as he recovers from a right hamstring strain suffered in Spring Training.

While Boston’s starting rotation has been the clear bright spot on the club even without Giolito, Nick Pivetta (right elbow flexor strain) and Garrett Whitlock (left oblique strain) are currently on the injured list.

And now the latest is losing Casas, one of the team’s most important bats, for an extended period.

“The [quality of the] at-bat, the power, working the counts, the on-base percentage, he’s a force,” said Cora. “We saw it last year in the second part of the season. He was really good. He’s very important, but we’ve got to keep going, man. We're not going to stop.”

The Red Sox did get some good news on the injury front on Tuesday as Tyler O’Neill returned to the lineup after spending seven days on the concussion-related injured list. Rafael Devers, the club’s most potent hitter, is expected to return Wednesday after being out of the lineup five consecutive games with a left knee contusion.