Updated

NEW YORK (AP) -- Dinelson Lamet made a splash for the San Diego Padres on Thursday night at rain-soaked Citi Field.

For the New York Mets, the season is teetering dangerously close to becoming a wash.

Lamet overpowered the Mets in his major league debut, New York's Rafael Montero labored on short notice and the Padres held on for a 4-3 win.

Scattered showers soaked Queens all day, and thunderstorms were forecast for midgame, although heavy rain never came. Mets manager Terry Collins pushed back scheduled starter Jacob deGrom to try avoiding an abbreviated outing, instead telling Montero around 3:45 p.m. that he'd start the 7:10 p.m. contest.

Montero (0-4) allowed two runs during a 45-pitch first inning, including a bases-loaded walk to Matt Szczur. Montero threw 87 pitches over three innings, giving up three runs, five hits and three walks. His ERA rose to 8.24.

"He was in constant trouble," Collins said. "The first inning, just fortunate we limited the damage to what he did."

Lamet (1-0) began his day by striking out Michael Conforto on three fastballs -- the last at 98 mph -- and cruised through five innings of one-run ball. The 24-year-old right-hander punched out eight and surrendered just three hits, including Lucas Duda's homer in the second.

The Padres rotation hasn't had a true fireballer this year, so Lamet's powerful fastball-slider combo gives San Diego a different look. He also impressed manager Andy Green with his changeup, a pitch Lamet said he's been working on, as well as his composure.

"I expected to see a little more emotion out of him," Green said. "He was relaxed all day."

Brad Hand allowed a run, but got the save by escaping a jam in the ninth for the second straight night. He got his first save of the season Wednesday.

Jay Bruce popped out in foul territory with a runner at first to end it. New York had runners reach base in each of the final five innings, including two on and two outs in the sixth and seventh innings, but left-hander Ryan Buchter evaded both jams.

The Mets have lost eight of their past 11 games and are well back in the NL East at 19-26.

Even red-hot Conforto had a miserable night. The leadoff hitter had struck out in five straight at-bats, including four on Thursday, before singling to right off Hand in the ninth inning.

The left fielder also lost sight of a pop fly during the third inning, covering his head while the ball dropped about 30 feet away just inside the foul line. Hunter Renfroe ended up with a double and later scored on Szczur's single.

"I just completely lost it," Conforto said, adding that he felt "helpless" once he lost track of the ball.

In the third, Jose Reyes doubled down the third-base line with Matt Reynolds at first, but the Padres executed a 7-6-2 relay with shortstop Chase d'Arnaud narrowly throwing out Reynolds at the plate.

San Diego rookie Allen Cordoba had two hits in his first game batting leadoff. Despite never playing above the Rookie-level Appalachian League before this year, the Rule 5 draft pick from St. Louis is batting .307.

Duda added an RBI single in the eighth.

Szczur has 15 RBIs in 15 career at-bats with the bases loaded.

TOO MUCH RELIEF

The Mets used at least three relievers for the 26th straight game, the longest run in team history by 11 games, according to the Elias Sports Bureau.

At least this time it was effective. Paul Sewald struck out four over three scoreless innings after Montero exited, and Josh Edgin followed with two more shutout frames. Addison Reed gave up a run in the ninth.

UP AND AT `EM

Collins has urged Montero to trust his stuff, not overthink and throw more strikes. Collins hoped that giving the swingman just three hours' notice might get him into more of a wind-and-fire mentality.

"We thought the later we told him, the less he could get anxious about it," Collins said, adding "he just didn't make any pitches early in the game."

TRAINER'S ROOM

Padres: OF Manuel Margot is out at least through Friday's game at Washington after experiencing tightness in his right calf this week.

Mets: SS Asdrubal Cabrera came off the DL and entered as a pinch hitter. C Kevin Plawecki was sent to Triple-A Las Vegas. … Bruce started in right field after leaving Tuesday's game with tightness in his back and sitting out Wednesday.

UP NEXT

Padres: Luis Perdomo (0-1, 5.79) gets the ball against Stephen Strasburg (5-1, 3.28) and the Washington Nationals to begin a three-game set.

Mets: DeGrom (3-1, 3.56) will start the opener of a three-game series against the Pirates, pushing Zack Wheeler back to Saturday. Chad Kuhl (1-4, 5.85) is coming off his best start this season for Pittsburgh, pitching five innings of one-hit ball in a 1-0 win over the Phillies on Sunday. Storms are forecast in Pittsburgh throughout the weekend.