The sellout crowd stood for most of the inning, twirling orange rally towels with each positive development.

After slogging offensively a night earlier and then clawing to a one-run lead Saturday, here was the daylight the Mets so desperately needed. Before that seventh inning concluded the Mets had sent nine batters to the plate, scored four runs and all but ensured another game in this series.

That winner-take-all will occur Sunday, following the Mets’ 7-3 victory over the Padres in Game 2 of the wild-card series at Citi Field.

Jacob deGrom and Edwin Diaz accomplished most of the heavy lifting from the mound. DeGrom allowed two earned runs over six innings and Diaz recorded five outs in the seventh and eighth as the Mets snapped a four-game postseason losing streak dating to the 2015 World Series.

The Mets led 3-2 in the seventh before loading the bases against reliever Adrian Morejon. Jeff McNeil stroked a two-run double to provide a cushion and the Mets added additional insurance on Eduardo Escobar’s RBI single and Daniel Vogelbach’s sacrifice fly.

“That was a very good Mets win,” McNeil said. “That is kind of the way we like to play baseball there.”

Buck Showalter credited his hitters for their patience with so much on the line.

“I’m proud of everybody, the discipline it takes,” Showalter said. “When you want something your tendency is to go get it physically instead of staying with it. That’s a real tribute to the players.”

The series will be resolved Sunday, when Chris Bassitt gets the ball against Joe Musgrove to decide who will face the Dodgers in the NLDS.

DeGrom gutted through six innings and allowed two earned runs on five hits with two walks and eight strikeouts. At 90 pitches, deGrom returned to pitch the sixth and retired the side in order. Diaz faced four batters in a shutout seventh and returned to the mound with a five-run cushion in the eighth and got two outs. Adam Ottavino walked in a run with two outs in the ninth and exited with the bases loaded before Seth Lugo entered to retire Josh Bell.

Diaz said his extended outing won’t preclude him from pitching Sunday if needed.

“If they need me more than three outs I will be ready because we have to win [Sunday],” he said.

The Mets needed the solid outing from deGrom, a night after Max Scherzer allowed four home runs and was removed after 4 ²/₃ innings. DeGrom’s performance was an improvement over his last, in which he allowed three runs (all on homers) over six innings against the Braves.

DeGrom, who has repeatedly said he intends to opt out from his contract after the season, said it entered his mind before the game that he might have been pitching for the last time with the Mets.

“But the hope was we would win a baseball game and continue to keep playing,” he said. “The goal was to put us in a position to win or give us a chance and pass it on to Bassitt. So our guys did a good job of coming out and putting together good at-bats and getting Blake [Snell] out of there early and putting up some runs late.”

Francisco Lindor’s two-out homer in the first against Snell gave the Mets a 1-0 lead. It was an inning in which the Mets put four runners on base, but scored only once. Brandon Nimmo singled leading off the game and was erased as part of a double play on Starling Marte’s sharply hit ball to third base. Following Lindor’s homer, Snell walked Pete Alonso and Mark Canha before retiring McNeil to conclude the inning.

Trent Grisham’s second homer in as many games tied it 1-1 in the fourth. The blast was the fifth allowed by deGrom over his last three starts, including three homers surrendered in Atlanta to conclude his regular season.

Nimmo’s third single of the game to the left side gave the Mets a 2-1 lead in the fourth and ended Snell’s night. Snell walked Escobar and Darin Ruf to begin the inning before Nimmo delivered. Overall, the left-hander finished with four hits allowed and six walks over 3 ¹/₃ innings. Nick Martinez entered and retired Marte and Lindor to prevent further damage.

Jurickson Profar delivered an RBI single in the fifth that tied it 2-2 against deGrom, who walked Grisham to begin the inning. Austin Nola’s sacrifice bunt moved the runner before Profar delivered. Juan Soto singled (and went to second on the throw) to put two runners aboard before deGrom struck out Manny Machado and Bell in succession to escape.

Alonso smashed the first pitch he saw in the fifth into the left-field seats for his first career postseason homer, giving the Mets a 3-2 lead. Alonso led the Mets with 40 homers and 131 RBIs during the regular season.

“I’m just so excited to come to the field [Sunday],” Alonso said. “This is what it’s for. I’m going to come ready to go.”