NEW YORK -- Pete Alonso hit the tiebreaking homer in the fifth inning and factored into a four-run seventh Saturday night for the host New York Mets, who forced a winner-take-all showdown in their National League wild-card series by beating the San Diego Padres 7-3.

The decisive game is scheduled for Sunday evening.

"This is why we play -- for those moments," Alonso said.

Chris Bassitt is expected to start for the Mets against fellow right-hander Joe Musgrove. The winner of the series faces the top-seeded Los Angeles Dodgers in the NL Division Series beginning Tuesday.

Francisco Lindor homered in the first and Brandon Nimmo had an RBI single in the fourth for the Mets, who stranded seven runners over the first four frames against Padres starter Blake Snell and Nick Martinez.

Alonso homered to left on Martinez's first pitch of the fifth.

Clinging to the one-run lead in the seventh and with the heart of the Padres' order approaching, Mets manager Buck Showalter went to All-Star closer Edwin Diaz, who hadn't pitched in the seventh inning of a regulation game since Aug. 2, 2020. Diaz gave up a one-out single to Austin Nola before retiring the top two batters in the San Diego lineup, Jurickson Profar and Juan Soto, on groundouts.

"I was ready," Diaz said. "They let me know before the game what their plan (was) with me. And I got to the bullpen early and I was ready to get the call from Buck.

The Mets sent nine batters to the plate in the bottom of the inning.

Lindor led off with a single and Alonso and Mark Canha drew walks during a pair of 10-pitch at-bats before Jeff McNeil doubled past a drawn-in infield. Eduardo Escobar followed with an RBI single, and Daniel Vogelbach lofted a pinch-hit sacrifice fly.

Diaz issued a walk and got the first two outs of the eighth before giving way to Adam Ottavino, who got the last out of the inning.

"If they asked me for more, I was ready," Diaz said. "I was feeling great. But they took me out because they need me for tomorrow. And we've got to win tomorrow's game."

Ottavino allowed a run before exiting after he issued a bases-loaded, two-out walk to Manny Machado in the ninth. Seth Lugo got cleanup hitter Josh Bell to ground out to earn the save.

Mets starter Jacob deGrom allowed the two runs on five hits -- including a game-tying homer by Trent Grisham in the third and a game-tying RBI single by Profar in the fifth -- and two walks while striking out eight. Soto followed Profar's fifth-inning hit with a single to put runners on the corners before deGrom struck out Machado and Bell.

"Love pitching here. Mets fans have been great to me," deGrom said. "Didn't want to disappoint."

Snell allowed two runs on four hits and six walks while striking out five over 3 1/3 innings.

"Obviously we would have liked to have done a little better tonight," Padres manager Bob Melvin said. "It got away from us in the seventh.

"Look, it's winner take all tomorrow, and I think they'll probably extend their guys even though they pitched some today as well."

--Jerry Beach, Field Level Media