DETROIT — Adam Ottavino’s first appearance since returning from the paternity list wasn’t exactly an “Oh, baby!” moment for the Mets on Wednesday.

The dependable right-hander was entrusted an eighth-inning lead in Game 1 of a doubleheader and got burned by a confluence of bad luck and one hittable pitch.

Eric Haase’s two-run single delivered the knockout punch in the Mets’ 6-5 loss to the Tigers at Comerica Park.

Jimmy Yacabonis pitched three shutout innings in relief, getting the ball to Ottavino in the eighth with the Mets ahead 5-4.

But Ottavino allowed a bloop single to Matt Vierling and drilled Javier Baez with a pitch before hanging a two-out breaking ball that Haase smashed for the go-ahead hit.

Ottavino’s blown save was the third by the Mets bullpen this season.

The right-hander had been perfect in his previous three save opportunities this year.

Joey Lucchesi lasted only four innings and allowed four earned runs on five hits with one strikeout.

The performance was the left-hander’s worst in three starts since his recall from Triple-A Syracuse.

Haase’s three-run homer in the first started the day in the wrong direction for Lucchesi, who allowed three hits in the inning.

Baez homered leading off the third for the Tigers’ fourth run against Lucchesi.

The Mets used the long ball to stay close before taking the lead: Tommy Pham homered leading off the second and Mark Canha’s blast later in the inning pulled the Mets within 3-2.

Pham snapped an 0-for-17 slump with his homer.

Francisco Lindor’s two-run homer gave the Mets a 5-4 lead in the fifth.

In the inning, Brett Baty and Tomas Nido each delivered a single and advanced bases on sloppy defense.

Baty took second on his leadoff single after center fielder Riley Greene misplayed it.

Nido followed with a single to left — on which Baty had stopped at third — but Andy Ibanez’s errant throw allowed the runner to score with Nido advancing to second.

With two outs, Lindor hit a shot into the left-field seats for his fifth homer.