NEW YORK -- The Mets’ bullpen took a hit Tuesday as the team announced that right-hander Robert Gsellman has suffered a partial tear of his right lat muscle.

An MRI exam revealed the tear, which could sideline Gsellman for a significant amount of time. Given this late juncture of the regular season, it’s possible that Gsellman could be done pitching for New York in 2019.

“I think it’s still, we don’t know how long this is going to last," Mets manager Mickey Callaway said before the game against the Indians on Tuesday. "So it didn’t really change our view on timeline or anything like that. It’s just unfortunate he’s not going to be available to us."

Gsellman has tossed 63 2/3 innings for the Mets this season, posting a 4.66 ERA and a 21.7% strikeout rate that mirrored his 2016 breakout campaign. After a slow start, Gsellman had lowered his ERA all the way to 2.48 in mid-May and had maintained a serviceable 3.72 ERA and .388 opponents' slugging percentage since the calendar flipped to July. Gsellman's most recent appearance was on Aug. 11, and the Mets placed him on the 10-day injured list with right triceps soreness on Saturday, retroactive to Aug. 14.

With Gsellman’s initial injury being triceps soreness but the MRI revealing a torn lat, Callaway was asked how the diagnosis could’ve changed.

“I think like a lot of things, injuries can present themselves in other places and it’s a byproduct of what you’re trying to protect ... you kind of overcompensate with other muscles to protect the muscle that’s injured,” he said.

The Mets’ bullpen as a whole has improved since the All-Star break, posting a 4.03 ERA as a unit in the second half after recording a 5.63 ERA before the Midsummer Classic. New York entered Tuesday night's series opener against the Indians two games back of the Cubs for the second NL Wild Card spot.

“[It’s] very frustrating, no one wants to be hurt,” Gsellman said Tuesday at Citi Field. "With the way the team’s playing, I want to be with them. But I’m still going to be here. I’m going to work my butt off to try to get back and support the team.”

Other injury updates

• Brandon Nimmo, who has been out since late May with a neck injury, played center field for Triple-A Syracuse on Tuesday as he continues a rehab assignment. He played games for Class A Advanced St. Lucie this past Friday and Sunday before moving on to Syracuse.

“That makes us feel more optimistic about him coming back and helping us, because we can use him,” Callaway said. “He’s a great player, he’s a bat, he can play center field, he can play left or right, and that versatility and that on-base and that power that he brings is very valuable, so we’re excited that he’s in Syracuse tonight.”

Asked for an expected quantity of games Nimmo might play with Triple-A before returning, Callaway said that determination has yet to be made.

“He’s been out a long time. We want him to feel totally comfortable in the box, we want him to feel totally comfortable out there in the outfield. So we’re going to really lean on him, so we really don’t have a set number of games,” Callaway said.

• Jed Lowrie, who has yet to play for the Mets this year due to a knee injury, hamstring strain and calf strain, was the designated hitter for St. Lucie on Tuesday. He previously was on a rehab assignment in May but was shut down from that with the latter two injuries.

“It’s still a situation where it’s going to be day to day obviously, but for him to get on the field and get his blood flowing in a big situation for him, to this point, is exciting, and I think that we’ll just see how he comes out of it and then make the schedule out the next day,” Callaway said.

Callaway indicated that perhaps Lowrie’s injuries are not completely gone yet, but that this is a good step.

“He’s in a good enough spot to go out and DH today. He’s done a great job with his rehab, he’s progressed well enough to where we feel he’s going to be safe DHing today, but like I said, you can’t predict anything with injuries,” Callaway said.

• Jeff McNeil, who has been out for a week with a strained left hamstring, is eligible to return from the injured list on Saturday. Callaway said the team has yet to decide on a day to activate him.

“He had a good day today,” Callaway said. “He went out, he took BP, he ran the bases, he looked really good running the bases and he always looks good swinging a bat, so BP was good. We don’t have a timeline. We’ll see how he comes out of today, but today was a good day for him.”

Roster moves

The Mets also made some roster moves Tuesday, selecting the contract of outfielder Rajai Davis from Triple-A Syracuse for his second stint with the big league club this season. In a corresponding move, the team optioned righty Walker Lockett to Triple-A. To make room for Davis on the 40-man roster, the Mets designated for assignment righty Brooks Pounders.

Davis' first stint with the Mets in 2019 began in dramatic fashion, as he made his Mets debut May 22 against the Nationals after taking an Uber from Lehigh Valley, where the Syracuse Mets were playing at the time, to Citi Field in time to hit a pinch-hit three-run home run off Sean Doolittle in the bottom of the eighth to help the Mets to a win. That first stint lasted four games for Davis, who is in his 14th Major League season.