Mets relief pitcher Dedniel Nunez delivers against the Nationals during...

Mets relief pitcher Dedniel Nunez delivers against the Nationals during an MLB game at Citi Field on July 11. Credit: Kathleen Malone-Van Dyke

PHOENIX — One game into his return from the injured list, Dedniel Nunez is hurt again.

The Mets put the righthanded reliever back on the IL on Thursday, prior to their 3-2 win over the Diamondbacks. The listed ailment was almost the same as last time: right forearm tightness, which sounds less severe than his initial strain.

Nunez will head to New York for a fresh MRI, manager Carlos Mendoza said. In the meantime, the Mets will operate without one of their better bullpen arms.

“It’s a big loss, but guys will step up. We’ve done it the whole year,” Mendoza said. “Guys will come up and the guys that we got in that room will continue to get huge outs. We did it today and we will continue to do it.”

In backdating the move the maximum three days, the Mets ensured Nunez will be eligible to return as soon as Sept. 10.

Previously, Nunez missed a month with a forearm strain but returned to the roster last Friday. He pitched Saturday against the Padres — 1 2/3 innings, 28 pitches — and felt fine. That night, though, his forearm started to bother him, he said.

“It’s a similar feeling, but this time it’s less pain and less discomfort,” Nunez said through an interpreter. “So what we decided to do was to not try to push it, for it to spiral into something bigger. So that’s why we decided to go on the [injured] list.

“It’s a little frustrating to be able to come back and get that adrenaline, be able to do your job and be able to help the team [only to get sidelined again]. It’s definitely frustrating.”

The Mets did not call up anybody to fill Nunez’s spot. But it did make room on the roster for Tylor Megill, who will return from Triple-A Syracuse to start against the White Sox on Friday.

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