NEW YORK – For the Mets' first 23 innings out of the All-Star break, the National League East leaders searched fruitlessly for the big hit. Pete Alonso -- who else? -- finally delivered it. And then some.

Alonso crushed a go-ahead three-run homer 425 feet to left-center-field off Joe Musgrove to spark the Mets to an 8-5 win over the Padres in Sunday night's series finale at Citi Field. The sixth-inning drive was his 25th home run of the season.

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"We hadn't really gotten it done," Francisco Lindor said. "Pete giving us the first lead of the whole series, it gave us a little boost. We got going. It was just a matter of us getting the wheel going, and Pete got it for us."

The next inning, Polar Bear Pete drove in his 82nd run of the season on a double high off the wall in right-center field, just over center fielder Esteury Ruiz's glove. That fourth RBI vaulted Alonso over Aaron Judge for the Major League lead -- right as the two New York All-Star sluggers prepare to face off in the week ahead.

"I would definitely put him in that elite group [of hitters]," said Daniel Vogelbach, who made his Mets debut on Sunday. "You see it from the other side of playing against him, but it's a lot better to be on his team."

On the eve of the Subway Series, Alonso and Judge showed why the clash of crosstown rivals will center on two of the slugging titans of baseball going toe to toe. Both Alonso and Judge homered to lead their teams to wins on Sunday. Alonso now has the edge in RBIs; Judge leads the MLB home run race with 37.

"I wouldn't really call it toe to toe, me vs. him,” Alonso said. “This is the New York Mets vs. the New York Yankees. This is going to be a great moment for New York. You've got two excellent teams that are in first place playing against each other."

The three runs Alonso provided with one swing on Sunday were the big ones for a Mets lineup that had managed just two in total against the Padres entering the sixth inning of the third game of the weekend -- and just one in 17 innings against San Diego's playoff-caliber starting pitching trio of Musgrove, Blake Snell and Yu Darvish. 

Despite running out three playoff-caliber starters of their own -- Max Scherzer, Chris Bassitt and Carlos Carrasco, who held the Padres to four runs in 18 innings themselves -- the sputtering offense had the Mets at risk of being swept by one of the NL's other strongest teams, with their lead over the Braves in the division dwindling as the 66-win Yankees loomed.

"You just can't get swept," Alonso said -- not even by a team like San Diego, which Alonso said he expects to be playing in the postseason.

Alonso's big swing off Musgrove, who carried a 2.31 ERA into that inning, took the pressure off. The Mets scored five runs in the sixth, getting a pair of key two-out RBI hits by bottom-of-the-order hitters Luis Guillorme and Tomás Nido after Alonso's home run, and three more in the seventh to blow the game open. Now they're going into the Subway Series on a high note.

"Sometimes you want something too much, and something like [Alonso's home run] might let you get back into the flow of who you are and who you want to be," manager Buck Showalter said. "But a two-run lead against that club? That's a good baseball team with a really good pitching staff. We'll let somebody else tangle with them for a while."

All series, Showalter and the Mets talked about needing to beat top-flight starting pitching like they've done throughout the season, and to come through with the clutch hit. It took the rock of their lineup to make both those things happen.

"We just ran into two buzz saws," Alonso said. "Yu Darvish, he's a multi-time All-Star, and then obviously Blake Snell has Cy Young capabilities. When you get guys with that type of stuff that are on, it's tough. Joe Musgrove, he's a hell of a pitcher, he's an All-Star. So we did a really good job today. We needed this one. This one was huge for us today."