The 4-2 series-opening win over the Padres gave them three in a row, putting them back over .500 at 37-36.
"That's what this team does, just battles until the very end," Piscotty said.
The A's had just four hits to their name when Piscotty stepped to the plate with two outs in the ninth. Down to his final strike against Padres closer Brad Hand, Piscotty launched a game-tying homer for his fifth long ball of the season.
"I think going into that at-bat, you know you're probably only going to get one good pitch to hit and you don't want to miss it," said Piscotty, 5-for-7 lifetime against Hand. "He did a good job getting ahead, but in my mind I was just waiting for that one, and luckily I got it and didn't miss it."
"If there's someone you want up against [Hand] based on his numbers, it's [Piscotty]," A's manager Bob Melvin said. "He's had the most success and faced him the most times. We really didn't do anything offensively, and for the most part, neither did they. Next thing you know, we tie it up and hit two homers, which typically we do when we win. Certainly a completely different game at the end of it than it was at the beginning."
The A's, dormant for much of the night, didn't wait long to strike again. Marcus Semien singled with one out in the 10th, advanced to third on catcher Raffy Lopez's throwing error, and scored the go-ahead run when Lowrie lifted one to right field off righty Adam Cimber for his 10th of the year.
Oakland closer Blake Treinen worked a scoreless 10th for his 16th save, while righty Lou Trivino -- who worked a clean ninth -- picked up the win in front of a hearty crowd that featured hundreds of A's fans.
"When you're down to your last strike and a guy hits a homer off one of the better closers in the game, that's a huge momentum shift," Lowrie said. "I was just looking for something I could square up. He made a mistake right down the middle."
A's starter Paul Blackburn wasn't at his best in the early going, but retired 11 of his final 12 batters. He needed 46 pitches to get through the first two innings, yielding a run in each of them. His issued a walk to his second batter, Cory Spangenberg, who would score the game's first run, and surrendered doubles to Franmil Reyes and Raffy Lopez in the second that pushed the Padres ahead.
Oakland was awarded an unearned run in the second, but it was an otherwise lackluster showing against Padres starter Eric Lauer; he allowed only three hits and struck out seven over six innings.
The A's woke from their slumber not long after.
"We've seen Jed have his flair for the dramatics," Melvin said. "It all started with Piscotty homering and the momentum shift. Once we got a guy on base, we felt good about where we were."
SOUND SMART The A's have homered in 20 consecutive road games, which is the second longest streak in franchise history. The longest is 21 games, from July 21 to Sept. 13, 2013.
HE SAID IT "That's a guy you don't typically think you're gonna string some hits together against. You're down to your last pitch, and next thing you know, it's a homer. That's about as big a momentum shift as you're gonna get, when you're a strike away from losing and then, all of a sudden, now you potentially have their closer out of the game and you feel like bullpen-wise, we're maybe a little more set." -- Melvin, on coming back vs. Hand
MITEL REPLAY OF THE DAY While attempting to turn Olson's ground ball into a double play in the second inning, Padres shortstop Freddy Galvis came off second base. Khris Davis was called safe after a replay review, and Mark Canha delivered a single to load the bases, setting up Piscotty's run-scoring double play ball.
UP NEXT The A's will turn to right-hander Frankie Montas (3-1, 2.67 ERA) in Wednesday's 12:40 p.m. PT series finale against the Padres. San Diego will counter with left-hander Joey Lucchesi, who will be activated from the disabled list after missing five weeks with a right hip strain.
Jane Lee has covered the A's for MLB.com since 2010. Follow her on Twitter @JaneMLB.