If this is Pete Alonso’s Mets swan song, it’s not going to be one he or the Amazin’s want to remember.

Already 0-for-3 in Thursday’s win-to-go-home wild-card Game 3 against the Brewers, Alonso whiffed on catching a pop-up in foul ground in the eighth inning in what almost was a complete disaster for the Mets.

With runners on second and third and two outs in the bottom of the seventh inning, William Contreras lofted a high pop-up near the first-base stands.

Alonso, a pending free agent, drifted toward it and camped under it need the protective netting, had room for it but dropped the ball as it landed foul.

Edwin Diaz, however, bailed him out, striking out Contreras to quell the threat and keep the Brewers at a 2-0 lead.