Oblique sidelines Swarzak

It was all going so swimmingly for the Mets.

Then Anthony Swarzak grimaced and favored his left side as he stood on the mound in the eighth inning Saturday at Citi Field.

The Mets’ new reliever had just issued a walk to Jose Martinez, and pitching coach Dave Eiland was headed to the mound for a check-in. It took just a few seconds before he was signaling for the trainer and manager Mickey Callaway, and soon, Swarzak’s day was done with what the club called a “sore left oblique.”

“I’ve never felt anything like this in my side before,” Swarzak said after a 6-2 win over the Cardinals. “I’ve not really been an injury-prone kind of person.”

Swarzak is day-to-day and will be re-evaluated Sunday. He said there weren’t any tests planned.

Making his second appearance in as many games, Swarzak had started off strong Saturday. He entered with one out and runners on second and third in the seventh inning as the Mets led, 4-1. The 32-yearold righty caught pinch-hitter Greg Garcia looking at strike three on a full count then got Dexter Fowler to fly out to center field to escape the jam cleanly.

Swarzak struck out Tommy Pham to lead off the eighth inning before allowing a solo home run to Matt Carpenter. He got the second out on Marcell Ozuna’s flyout, but after walking Martinez on seven pitches, he began to stretch out his left side.

“I felt good, no doubt, and then I threw one pitch and it didn’t feel so good,” Swarzak said, adding he either injured himself on the last pitch to Pham or the first pitch to Carpenter. “We’ll see what happens. I’m optimistic. I’m not panicky at this point, we gotta see what’s going on. Hopefully I feel better [Sunday], and this is just a little scare.”

A strained calf had sidelined Swarzak for a little more than two weeks during spring training after signing a two-year deal worth $14 million in December, but he came out of camp with a clean bill of health.