SAN DIEGO — Austin Warren has become indispensable to the Mets bullpen based on his versatility and success, but Saturday night brought maybe his most glaring hiccup this season.

Given a one-run lead to protect, the right-hander got two fast outs in the seventh inning.

A squib deflected by Warren for an infield single followed before Freddy Fermin smashed a two-run homer that became the Mets’ margin of defeat in a 3-2 loss to the Padres at Petco Park.

The Mets, after two straight victories in which the lineup produced, reverted to a familiar refrain of offensive silence.

The loss left the Mets needing a win on Sunday to reach .500 for the road trip.

Warren’s letdown was an anomaly for a bullpen that began the day with a 3.19 ERA that ranked third in the National League and fifth in MLB.

Austin Warren throws a pitch for the Mets during their June 6 loss to the Padres. Imagn Images

The right-hander had pitched to a 1.33 ERA, filling a variety of roles, from opener to long relief to higher leverage.

“I didn’t do my job, plain and simple,” Warren said. “I needed to get my outs, and I didn’t get my outs.”

Nolan McLean recovered from an elevated pitch count early to give the Mets six innings, allowing one earned run on three hits and three walks with five strikeouts. McLean snapped a string of three straight starts in which he failed to complete six innings and lowered his ERA to 3.98, departing after 101 pitches.

“I feel like I was trending in the right direction further down in the game than when I started so that is always a good sign,” McLean said.

Griffin Canning, who pitched last season for the Mets before undergoing June surgery for a ruptured Achilles, provided resistance against his former team.

The right-hander surrendered one earned run on three hits and two walks over five innings.

Brett Baty’s RBI single in the second gave the Mets a 1-0 lead.

Marcus Semien walked and A.J. Ewing singled to begin the rally before Baty delivered for his 25^th RBI of the season.

It was a welcomed contribution from Baty following his 3-for-16 (.188) start   to the road trip.

Fernando Tatis Jr. stroked an RBI single in the third that tied it 1-1.

McLean created trouble by walking Sung-Mun Song leading off the inning.

After Song stole second Tatis grounded a shot that hit off second base and deflected past Marcus Semien for the run.

McLean walked Ty France with two outs, but escaped by striking out Manny Machado. Even so, McLean ran his pitch count to

Freddy Fermin reacts after hitting a home run during the Padres’ June 6 win over the Mets. IMAGN IMAGES via Reuters Connect

62 pitches by the end of the inning.

Semien singled in the fourth before he was thrown out attempting to steal second base.

Ewing followed with a walk before Canning struck out Mark Vientos to end the inning.

Song singled leading off the fifth and reached third following a sacrifice bunt and Tatis’ infield single.

With two outs, the Padres attempted a double steal — with Song breaking for the plate on a delay.

Luis Torrens pump faked to second and held the ball, catching Song in a rundown, with McLean applying the tag for the out.

Semien homered leading off the seventh to give the Mets a 2-1 lead.

Marcus Semien reacts after hitting a home run during the Mets’ June 6 loss to the Padres. AP Photo

The blast was Semien’s seventh this season. Semien began the day in an 0-for-14 drought, but reached base three times on this night.

Warren got two outs in the seventh before Song’s infield single.

Fermin blasted a first-pitch sinker over the left-field fence.

---

• CHECK OUT THE LATEST MLB STANDINGS AND METS STATS

---

Carson Benge and Bichette each singled with one out in the eighth.

Juan Soto hit a smash that was caught by Song, and Benge was caught off second base to end the inning.

“That situation, obviously, the line drive you cannot get doubled off,” manager Carlos Mendoza said. “But it was 101 [mph] off the bat and that’s a tough one there. It’s a tough read, especially when it’s a hard line drive off the bat.”

Ewing walked with two outs in the ninth against fire-balling Mason Miller before Vientos struck out to end it.