New York Mets ace Max Scherzer is headed back to the injured list, the latest hit to a reeling club that has seen its National League East lead evaporate.

The Mets placed Scherzer on the 15-day IL, retroactive to Saturday, with left side irritation amid a series of roster moves before Wednesday's doubleheader against the Pittsburgh Pirates.

Mets manager Buck Showalter said the team expects Scherzer to miss one or two starts, and the star right-hander echoed those sentiments, saying the injury will sideline him for "days, not weeks."

"That's the first and foremost thing -- this is not a significant injury," Scherzer said. "This is more that I'm going to miss one start -- we knew that -- and then once the ball's out of my court, the team's gotta do what they gotta do for roster moves."

Scherzer said his left side "just feels achy" and emphasized that he does not have a muscle strain in the area.

"I don't have one specific spot that you can point to where that hurts," he said. "It's just general fatigue on the whole left side."

Scherzer was sidelined for nearly seven weeks earlier this season with a left oblique injury, but Showalter said that the Mets anticipate the three-time Cy Young Award winner will return in time to "finish the season strong."

"It was actually pretty good news, all things considered, that there wasn't something torn or where he had [the injury] last time," Showalter said. "I think the idea is to get it resolved so that he can finish the season strong and be ready for whatever the season holds for us."

"The first time I did this, I had one specific spot [that was injured]," Scherzer added. "That's not what this is, so that's the good in this."

Scherzer's latest IL trip, however, could not have come at a worse time for the Mets (85-51), who have lost five of their past eight games, including three straight against the last-place Washington Nationals and the Pirates. New York owned a 10½-game NL East lead on June 1, but it enters Wednesday's doubleheader in Pittsburgh tied with the surging Atlanta Braves (85-51) atop the division standings.

In corresponding roster moves, the Mets selected the contract of left-hander Alex Claudio from Triple-A Syracuse, recalled right-hander Yoan Lopez from Syracuse and designated right-hander Adonis Medina for assignment.

Scherzer, 38, is 9-4 with a 2.26 ERA in 20 starts this season, his first with the Mets. After experiencing fatigue in his left side during Saturday's start against the Nationals, the eight-time All-Star left despite having thrown just five innings and 67 pitches.

Scherzer, who had been expecting to make his next scheduled start Friday against the Miami Marlins, said he had "no regrets on how I handled the situation" against the Nationals.

"I communicated my symptoms and kind of had conflicting symptoms throughout the game," he said. "I felt fatigued, but I was still out there throwing the ball well and went as far as I could."