In a text message to MLB.com, Niese downplayed the severity of the pain, saying it felt nothing like the partially-torn left rotator cuff that sidelined him for eight weeks last season.
"There's no pain, just a little discomfort," Niese wrote. "Last year when there was pain, it was difficult to do everyday things such as turn a steering wheel or simply put on a belt. There's no pain with any of that now, so I don't foresee it being serious at all. Just going to take a look at it to make sure, so I can move on with Spring Training, so I don't miss any of the season."
"He just said he's got a little discomfort in there," Collins said, "so we're going to have a look."
Collins said that Niese began experiencing "a little bit of pain" in his left triceps after reporting to camp, but that it was not in the same area as last year's issue. Niese ultimately rehabbed his rotator cuff non-surgically last summer, returning to go 5-2 with a 3.00 ERA in 10 starts down the stretch. He finished 8-8 with a 3.71 ERA in 24 starts overall.
According to Collins, Niese first reported discomfort early in camp, prompting the Mets to limit him to long-toss. The left-hander climbed back upon a mound this week and initially felt fine, but the second half of his live batting practice session Monday resulted in pain. As a result, the Mets decided around noon Wednesday to fly Niese to New York for testing.
"He just said at the end of it, 'Geez, my arm's just dead,'" Collins said. "'Like, it's dead.'"
Niese, 27, is entering the third season of a five-year, $25.5 million deal that includes team options running through 2018. He started Opening Day for the Mets last season, and was the leading candidate to do so again on March 31 against the Nationals. If Niese is not healthy enough to make that start, Bartolo Colon and Dillon Gee would be the frontrunners to replace him.
Colon, incidentally, is also nursing a minor injury, skipping Wednesday's workouts with tightness in his calf. Outfielder Eric Young, Jr. is battling midsection soreness as well, though the Mets do not consider either injury serious.