MILWAUKEE -- Come October, the Padres were always going to sink or swim with their bullpen -- the best in baseball all summer long.

They haven't been sunk just yet. But they’re taking on water after a stunning 4-3 loss to the Brewers on Sunday afternoon at American Family Field in Milwaukee.

Brewers left fielder Jackson Chourio hit a walk-off two-run single against San Diego's superstar closer Mason Miller, who was one strike away from his first six-out save as a Padre.

Miller loaded the bases in the ninth with a trio of walks, but got ahead of Chourio, who fought his way back into the count. Miller threw a 2-2 fastball and Chourio swatted it into center field, just past the outstretched glove of Padres second baseman Jake Cronenworth.

And with that, the Brewers carry a 2-0 series lead back to San Diego. The Padres, of course, have been a juggernaut at Petco Park this season, with a 53-30 record, including a pair of playoff wins already. But they’ll need to win two straight Tuesday and Wednesday just to send this series back to Milwaukee for a decisive Game 5 on Friday.

And the most agonizing part? They could’ve -- maybe should’ve -- won both. At least, both times, the game was in the hands of their lockdown bullpen. They wouldn’t want it any other way.

Which made the ending so unbelievably cruel.