Injured back keeps Bruce out of lineup

Jay Bruce’s back is a bigger issue than he believed.

The Mets outfielder was scheduled to return to the lineup Saturday after leaving the previous night’s game with back spasms, but Bruce was scratched from the lineup two hours before the Mets lost 7-1 in 14 innings to the Cubs at Citi Field.

Prior to the game, Bruce said he was feeling better and was confident he would play, but the 31-year-old said his back didn’t loosen up as he expected and didn’t start as a precautionary move.

Bruce entered as a pinchhitter in the eighth inning and struck out.

“I’ve got a pretty good pulse on how my body feels, what I can play through and not play through and stuff like that,” Bruce said before warming up.

Bruce expects to play Sunday and said the injury likely stemmed from improper stretching before playing first base Thursday night.

The rotation for next week is nearly set and could conclude with Noah Syndergaard taking the mound when the Yankees come to Citi Field.

Syndergaard, currently on the disabled list with a strained ligament in his right index finger, played catch prior to Saturday night’s game against the Cubs and could throw a light side session Sunday.

Todd Frazier went 1for-3 and played seven innings for Triple-A Las Vegas on Friday night, and was scheduled to play nine innings Saturday.

The third baseman has been on the disabled list since May 8 with a left hamstring strain.