Just as he was beginning to find a groove out of the Mets bullpen, Trevor May landed back on the injured list Saturday.

The Mets did not give an injury designation for May, which in the past has signaled a COVID situation. Manager Buck Showalter said after the Mets’ 7-1 loss to the Nationals on Saturday night that he could not offer further details.

Before going on the IL for the second time this season (the first was for a stress reaction on the lower portion of his humerus), May had started to look sharper, throwing three straight scoreless outings with five strikeouts across 2 ¹/₃ innings.

Hard-throwing right-hander Bryce Montes de Oca was called up from Triple-A Syracuse to take May’s spot in the bullpen and he made his MLB debut with one out in the ninth inning. He allowed a walk and a single, but recorded a strikeout and left the bases loaded in a scoreless two-thirds of an inning.

“You can see why everybody’s so high on him,” Showalter said of Montes de Oca. “He’s got a good arm and I like his delivery. We’ll see. He’s a guy that we think has a good future.”

The 26-year-old, who had struck out 72 batters with a 3.61 ERA across 47¹/₃ innings this year between Double-A and Triple-A, got a car service from Scranton, Pa., in order to arrive at Citi Field around two hours before first pitch.

“It’s pretty surreal,” Montes de Oca said. “Still haven’t all settled in really. It’s been a whirlwind of a day. But I’m happy to be here and excited to help out in any way I can.”

Tylor Megill (right shoulder strain) is set to make his second rehab appearance on Sunday, with Double-A Binghamton. The right-hander will return from the IL as a reliever, and looked good in his first rehab appearance on Thursday when he struck out the side in his one inning of work.

If his one-inning outing Sunday goes well, Megill will likely be transferred to Triple-A Syracuse, where he could build up to two innings.

The Mets are still determining whether Megill would be more valuable as a multi-inning reliever or as a reliever who can pitch on back-to-back days.

“That’s what we’re still trying to see,” Showalter said. “Right now, we’re trying to get him healthy, make sure that he’s recovering after every inning and everything’s fine structurally. And then we’ve got to decide whether we want him to be able to throw two innings with multiple off days or see if he can throw back-to-back.”

Drew Smith (right lat strain) also threw another bullpen session on Saturday, putting him in line to face hitters in live batting practice on Tuesday. If everything goes well with that, he should begin a rehab assignment by next weekend.

Lefty Joey Lucchesi (Tommy John surgery), who also is coming back as a reliever, made his fourth appearance Saturday night with Single-A St. Lucie. He threw two no-hit innings, with one strikeout, on 13 pitches.

“People think he could be a help either this year or next,” Showalter said. “We’re going to run down that path and see where we are as a club when we get to the point where he is an option.”

Luis Guillorme (left groin strain) is scheduled to begin a rehab assignment on Tuesday at Triple-A Syracuse. … Carlos Carrasco (oblique strain) will come off the IL on Sunday to start the series finale. After throwing 55 pitches in a simulated game on Monday, he will be on an unspecified pitch count while continuing to build up his workload.