FORT MYERS, Fla. -- Vaughn Grissom was expected to make his Red Sox debut this weekend. Instead, he’s now doubtful for Opening Day.

Manager Alex Cora revealed before Boston faced the Nationals on Saturday that Grissom, the Red Sox’s presumptive starting second baseman, was “shut down” with what Cora deemed a slight left groin strain he sustained on Thursday while completing fielding drills.

"I was just taking ground balls, and it bit me," Grissom said. "... Obviously, it [stinks]. New group, I want to be out there with the guys, so it's definitely frustrating."

Prior to the injury, Vaughn dealt with hamstring soreness in both legs that had kept him out of Grapefruit League action, but Cora said he had been “trending in the right direction” and was penciled in to play Sunday before an MRI revealed the groin strain.

“This happened, and now we just have to be patient, get him stronger, get him better, and he'll be OK,’’ Cora added. “... We’re obviously disappointed in a sense because we wanted Vaughn to get as many reps as possible and hopefully be the starting second baseman of the Boston Red Sox, but I think we've ... got a good [choice to step up].”

For now, it appears that Enmanuel Valdez will slot in at second in Grissom’s absence. Valdez landed with the Red Sox via the Christian Vázquez trade with the Astros on July 31, 2022, and brought with him a coveted left-handed-hitting option for the lineup. The 25-year-old slashed .266/.311/.453 across 49 games with the big league club last season and added 41 RBIs, 10 homers, two triples and eight doubles in 57 games with Triple-A Worcester.

The trouble for Valdez last season came in the field, where he committed seven errors in 357 innings at second base and had -7 Outs Above Average with the big league club last season. While it’s safe to assume some of that was due to first-year jitters -- Valdez made his MLB debut on April 19 -- he also ranked in just the eighth MLB percentile in arm strength (75.6 mph) in 2023. With less power comes lower velocity, and with it the tendency to hurry the fielding part of the bang-bang plays that can lead to miscues.

Valdez played for Toros del Este in the Dominican Winter League this offseason to log some extra work, and Cora was optimistic that that decision, in addition to extra reps on the back fields this spring, had changed his young potential second baseman for the better.

“I do believe out conversion now will come into play,” Cora said. “When you feel like you cannot finish plays with your arm, then you're going to rush; you're going to make bad decisions. And I believe that's what happened early on. He was better the second time he [was promoted from Triple-A], and now he's moving well, he's working hard. He's in constant communication with Trevor [Story], which is great.”

Pablo Reyes, who joined Valdez with the Toros in LIDOM this winter, gives the Red Sox a second capable option at second base as they await Grissom’s return.

Grissom was acquired from the Braves on Dec. 30 in the Chris Sale trade in the Red Sox’s attempt to bring some stability to a position that’s been a revolving door since Dustin Pedroia ended his longtime reign there in 2017. Grissom, whose path to a starting infield spot in the Majors was previously blocked by the Braves’ talented young core, said he chose to view the trade as an opportunity to “write my own book” with Boston.

He’d impressed everyone, from chief baseball officer Craig Breslow -- who said the club viewed him as someone who could play every day -- to Cora, who was “very excited” to see Grissom in action.

Grissom is a grinder, but he’ll have to shelve that mentality for a little while as he rests the strain. The setback is understandably frustrating to a player who prepared as much as possible for a crack at a starting role, only to lose it momentarily three weeks before Opening Day.

If there’s anyone who’ll be ready once he’s cleared though, it’s Grissom, who noted earlier in camp that adversity is one of his biggest motivators.

“I like to grind, and I love the doubt,” he said. “It's just something that drives athletes. Whatever situation I'm in, I don't just take it as a win or anything; I feel like I still have to go out and earn everything.”