PITTSBURGH -- The lineup the Red Sox used in their series finale vs. the Pirates on Sunday was admittedly one of their thinnest of the season. Misfortune spelled by multiple injuries to everyday starters made it that way.

Trevor Story is out for the season. Rafael Devers missed a handful of games after a bone bruise in his left knee, and Tyler O’Neill landed on the concussion IL due to an outfield collision.

The good news is that the Red Sox have been able to weather these injuries, sweeping the Pirates with a 6-1 victory at PNC Park on Sunday afternoon. The even better news is that manager Alex Cora is confident that Devers and O’Neill will return to Boston’s lineup on Tuesday in Cleveland.

The bad news is they’ll have to weather one more absence created by an injury to another everyday player: Triston Casas. The Red Sox’s first baseman was placed on the 10-day injured list with a left rib strain, and the team is concerned it could be a lengthier absence. Casas had produced an .857 OPS in his first 22 games of the season before he injured himself on a swing in his first at-bat on Saturday.

Casas said he felt something in the area in the team’s series vs. the Guardians earlier in the week, but it was milder and he knew the lineup needed his bat. Now, he’s at a point where it hurts to breathe.

“Just with where the team was at, I was trying to grind it out as long as I could before I really pulled the plug,” Casas said.

Any injury is tough, but the timing is brutal for the Red Sox. Devers and O’Neill took batting practice at PNC Park on Sunday, and Cora said Devers even asked if he could play on Sunday instead of waiting until Tuesday. With their availability all but written in pen for Boston’s next series, Cora anticipated having his power trio back together.

“It’s one of those [things] where you can’t think too much about Triston, because he’s not going to be here,” Cora said. “But the way he’s swinging the bat and these two guys in the lineup, having Tyler in between those two, I was looking forward to it. But now, we have to readjust, and we’ll be OK.”

So the Red Sox will have their depth tested once again, and in that sense, their first run at production without Casas was a good one. The lineup provided consistent pressure to a struggling Pirates team, including two RBI singles by Wilyer Abreu and a pinch-hit two-run knock by Reese McGuire.

The Red Sox have won four of their past five games working with a lineup at limited capacity, and they’re now 13-10, keeping pace in a hot American League East.

The biggest factor in that success has been the starting pitching. But what’s driving the offense?

“Youth,” Cora said. “They don’t know any better, some of them. They just show up every day willing to work.”

Abreu, the biggest bat in Sunday’s win, has played fewer than 50 MLB games. Cedanne Rafaela is not only at 51 games, but he’s also had to move from the outfield to shortstop with Story out. Though he struggled Sunday, Enmanuel Valdez entered the finale 6-for-22 with a double and a homer in his past seven games.

“We knew going into the year that the core of the team was going to be some young guys and rookies,” said Rob Refsnyder, the oldest position player on the roster at only 33 years old. “They’re learning on the go, and I think they’re doing a really, really good job in making those adjustments.”

Now, the team’s focus shifts to Cleveland, and the first task is filling the gap at first base. The duties were handed to Pablo Reyes on Sunday, and Bobby Dalbec is another option. Cora also mentioned Jamie Westbrook as a depth piece, and depending how long Casas’ stay on the injured list is, Romy Gonzalez -- who is recovering from a left wrist sprain -- could be a fit.

“There’s a lot of moving parts,” Cora said, “and I think tomorrow will be a great day for us to sit down and start thinking about Cleveland and the Cubs, and let’s see how long [Casas] is going to be out and decide what we’re going to do in the future.”

But despite it all, the Red Sox have gotten a jolt given the way they’ve played while as shorthanded as anyone in MLB.

“We’re just going to go out here and play with the 26 guys that we have, and we’re going to try to win every single game, fight ‘til the last pitch,” said rookie reliever Justin Slaten, who earned his first win. “Nobody comes in here sulking about who we have and who we don’t have. We feel confident.”