MILWAUKEE -- The season had all but ended. The Mets had all but boarded their flight home. Then Pete Alonso delivered the most significant hit of his life.

With the Mets down to their final two outs, Alonso hit a go-ahead, three-run homer in the ninth inning Thursday to send the Mets to a 4-2 win over the Brewers in National League Wild Card Series Game 3. The Mets advance to the NL Division Series against the Phillies beginning Saturday. The Brewers are going home.

After falling behind on back-to-back homers from Jake Bauers and Sal Frelick in the seventh inning, the Mets rallied on a leadoff walk and a one-out hit from Brandon Nimmo in the ninth. Facing Milwaukee closer Devin Williams, Alonso followed with an opposite-field, three-run shot, as the Mets came pouring out of their dugout to celebrate. For a moment, a sold-out crowd at American Family Field went silent.

Alonso is the first player in MLB history to hit a go-ahead homer while trailing in the ninth inning or later of a winner-take-all postseason game.

It was nothing short of a catharsis for Alonso, who came into the at-bat in a 5-for-41 slump with no extra-base hits and only one RBI since Sept. 19. Due to be a free agent after the season, Alonso not only extended his time with the Mets, but reframed the narrative surrounding the type of player he can be.

Starling Marte added an RBI single for the Mets to help make a winner of Edwin Díaz, who recorded five outs after the Brewers took the lead against José Buttó. Jose Quintana had blanked Milwaukee over the game’s first six innings. David Peterson worked the ninth for the save, getting Brice Turang to hit into a double play to end it.