Red Sox pitcher Kutter Crawford injured his right knee early last season and it is still bothering him. He is unlikely to be available at the start of the season. AP photo

PORT CHARLOTTE, Fla. — As they open Grapefruit League play Saturday afternoon against the Rays, the Red Sox are facing the possibility that their starting rotation won’t be at full strength when the regular season opens in just over a month.

Manager Alex Cora acknowledged Saturday that righties Kutter Crawford (right patellar tendon soreness) and Brayan Bello (right shoulder soreness) remain behind in their throwing programs, leaving Opening Day somewhat in doubt for both. It appears Crawford’s absence could be longer.

“With Kutter, that’s the one it looks like is going to be long,” Cora said at Charlotte Sports Park. “Opening Day, right now, is an ‘if.’ Let’s see what happens.

“He’s not feeling well. He’s behind. We’ve got to make sure the knee is good so the shoulder doesn’t suffer.”

Crawford dealt with knee soreness for most of his 33 starts in 2024 after tweaking it during an April outing. He hoped resting during the offseason would lead to a pain-free start to spring but he was sore in early throwing sessions. Crawford threw a bullpen at Fenway South on Friday after long-tossing Thursday; the pain was still present, according to Cora.

Bello reported to spring training with some shoulder soreness and has been slowing ramping up his throwing program in the early weeks of camp. Asked if Opening Day was on the table for him, Cora said the next week would be a telling one. Bello will have a strength test Sunday to determine next steps.

“We’ll make sure the plan fits what we need from him,” Cora said.

The Red Sox entered camp with six veteran starters — Bello, Crawford, Garrett Crochet, Tanner Houck, Walker Buehler and Lucas Giolito — in the mix. In the first week of exhibition play, only Crochet (Sunday), Houck (Monday) and Buehler (TBD) are expected to see game action. Giolito, who is in the final stages of his rehab from internal brace surgery last March, threw an up-and-down session on a back field Saturday and is likely to face hitters soon before getting into game action. There’s still time for him to be good to go for the start of the season.

For now, the Red Sox don’t know exactly when Crawford, Bello and Giolito will be good to go, leaving Crochet, Houck, Buehler, depth starters Cooper Criswell, Richard Fitts and Quinn Priester and dark horse Michael Fulmer in the mix for rotation spots. Cora expects the Red Sox will go with five — not six — starters to begin the year in Texas. Boston’s early-season schedule is daunting as the club has just one day off in the first 20 days of the regular season.

“We haven’t talked about a six-man (rotation),” Cora said. “You guys have talked about it. If we go that route, it’s for a reason. For right now, we’re taking the best five and using the bullpen the right way knowing we play five in a row, then an off day, then (15) in a row.”

THE RED SOX received relatively good on lefty reliever Zach Penrod but still expect him to miss a good chunk of time with an elbow injury.

Penrod’s MRI revealed no structural damage and he’s not a candidate for Tommy John surgery or another procedure, Cora said. After initial tests led to a pessimistic outlook on his status, more exams showed that his ulnar collateral ligament (UCL) is intact.

Still, the expectation is that Penrod won’t pitch anytime soon.

“He’s gonna be out for a while,” Cora said. “Nothing structural. Elbow inflammation, so we’ll shut him down for now. We’re not talking surgery but rehab and we’ll see how it goes.”