Three home runs in the first inning would seem to be an omen in any ballgame. So it was in this one, just not in the way you would think. This time it was the Mets who hit the three homers, and it proved ominous because it just gave the Dodgers something else for which to come back, back, back.

As if to say, “We’ll spot you three and take it from there,” the Dodgers — the team with the best record in baseball at 78-32 — answered with five homers of their own in Saturday’s 7-4 victory over the Mets at Citi Field. All 11 runs resulted from long balls in a game that kept both teams going, going, going the way they had been.

It was the Mets’ sixth defeat in the past seven games and their eighth in a row against the Dodgers dating to May 28, 2016. The Mets tied their season low at 10 games under .500 (49-59), with the possibility of more changes in the wind.

For the Dodgers, who strengthened a strong roster at the trading deadline, it was their 12th win in the past 13 games and 66th in 66 games in which they have led after the eighth inning. They have won 43 of their last 50.

It all appeared headed in a much different direction when Michael Conforto hit the second pitch from Rich Hill into the right-centerfield bullpen and Wilmer Flores and Curtis Granderson added home runs later in the first inning. On top of that, Mets starter Seth Lugo did not allow a hit until there were two outs in the fifth inning.

“We play nine innings for a reason,” Lugo said after leaving with the score 3-3 in the sixth, having allowed home runs by Chris Taylor, his 15th, and Cody Bellinger, his 31st.

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Said Neil Walker, “They’re firing on all cylinders. You know you’re going to have your hands full every single time you’re out there from many different angles. They’ve done a nice job with trades and bringing people in.

“We were hoping to build on the momentum we gained in the first inning and we weren’t able to do that. To Hill’s credit, he threw the ball better after the second inning. Obviously, they’ve got a really good bullpen, too.”

It wasn’t until Rene Rivera’s homer against Ross Stripling in the ninth that the Mets scored again. It was too late. “That’s why you’ve got to add on, just as they did,” Terry Collins said.

As odd as it may sound for a team so far out of the race, Collins spent 35 minutes before the game on the daily problem of actually having too many players. He decided to sit Jose Reyes and Jay Bruce. The logjam might be eased with a deal, considering that both Granderson and Bruce have cleared waivers, as Ken Rosenthal of Fox Sports reported Friday. “We’ve got guys who have been a big part of this team for two years and they deserve the right to get in that lineup once in a while,” Collins said.

But it was the Dodgers who flexed their depth, with a lineup that has power hitter Yasiel Puig batting eighth. He led off the seventh against losing pitcher Paul Sewald (0-4) with his 21st homer to put the Dodgers up for good. Justin Turner led off the eighth with a homer (No. 12) against the same pitcher, making it 5-3. Corey Seager hit his 19th of the season, a two-run shot off Fernando Salas in the ninth.

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“With most lineups, there’s a couple guys where you can walk them and get to an easy out. There are no easy outs,” Lugo said. “Every one of them, you’ve got to bear down and make pitches. You see what happens when you make mistakes.”

This is what happens: You allow 23 homers in six games against them, as the Mets have this season. It leads to a tough ending, even on a day that started with such promise. “Yeah,” Collins said, “it’s frustrating.”

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