SAN DIEGO -- If the Padres’ outing against the Mets on Saturday night was a fish, they might just throw it back.

Things were a tangled mess from the get-go for San Diego as it dropped its third game in four days, losing to the Mets, 7-1, at Petco Park.

San Diego’s bats were tepid, getting a run on six hits. The Padres’ defense committed two errors, which led to four unearned runs. San Diego’s four hurlers allowed three home runs -- one a grand slam -- three walks and a hit batter.

Some unfortunate circumstances compounded the rough going, and the result for starting pitcher Michael King was predictable.

“Definitely a tough-luck night,’’ Padres manager Mike Shildt said. “I thought Michael pitched the ball well -- better as he went on. It just wasn’t his night.”

King escaped a first-inning, bases-loaded jam when allowing just one run. His fortunes flipped in the fourth, when the Mets had the bases full until Francisco Lindor emptied them. Lindor demolished an 81 mph sweeper, depositing it in the right-center-field seats to extend the Mets’ cushion to 5-0.

“Couple of bad pitches, and I felt like I didn’t read swings correctly on a few sequences that I called,’’ King said. “I didn't make a pitch that I needed to.’’

King was second-guessing his offerings to Lindor. He gave the Mets’ star a steady diet of sweepers and changeups.

“With an elite hitter, you are not going to miss those opportunities,’’ King said. “I did the exact sequence as I had done before.”

There were unlikely fingerprints on the Mets’ breakthrough. Manny Machado misplayed a line drive into an error, which led to Lindor’s seventh career grand slam.

The play that Machado didn’t make was one he usually does.

“I just lost it in the stands, and it just hit the tip of my glove,’’ Machado said. “We could have got out of the inning and we gave up four.”

Shildt’s take on Machado’s miscue?

“He was a human for a moment,’’ Shildt said. “The guy is one of the best third basemen to ever play the game, and sometimes you have to prove that you are human.’’

The right-handed King worked five innings and allowed five runs (one earned), three hits, three walks and a hit batter, with seven strikeouts.

The Mets struck first on a wacky play, during which a broken bat was flying into short left field and a batted ball had eyes for third base.

King, who labored through a 31-pitch first inning, walked Mark Vientos and Brandon Nimmo. Pete Alonso followed with a one-out dribbler up the third-base line that shattered his bat. Machado was primed to turn a potential double play, but the ball kissed the corner of the bag and ricocheted into foul territory, allowing Vientos to score.

Still, Shildt loves what he sees from King. For the Padres to reach the postseason, Shildt is confident King will pitch royally.

“He’s been big for us, and he is only going to continue to be big for us,’’ Shildt said. “He is going to win some big games for us down the stretch.’’

Trailing 5-0 in the fifth inning, the resilient Padres, with 32 comeback wins, sniffed a rally. Kyle Higashioka and Mason McCoy got hits, with Bryce Johnson walking in between their knocks as the Padres loaded the bases.

But Mets left-hander David Peterson stymied the uprising by getting Luis Arraez (RBI) and Jurickson Profar to ground out, and that was as close as the Padres would get.

The Padres’ deficit became 6-1 in the seventh when Lindor greeted reliever Yuki Matsui with his second homer of the game.