Philadelphia catcher J.T. Realmuto tied it up with a two-run double in the fifth inning and launched a solo homer to push Philadelphia over the top in the 10th.
"It's incredible. I'm just so thankful for this opportunity," he said in a televised interview after the game. "I can't say enough about my team mates... That's a Phillies win right there."
It was a remarkable reversal of fortune for the Astros after a pair of homers from slugger Kyle Tucker and an RBI single from Martin Maldonado gave them what should have been plenty of cushion heading into the fourth inning.
See stats from the game at Flashscore
But the Houston offence could only watch helplessly as nine-time All-Star pitcher Justin Verlander, who had appeared rock solid through the first three innings, unravelled on the mound and their lead evaporated.
"I need to do better. No excuses," said Verlander.
"I just need to execute pitches better. I felt like I had some guys in good situations and just wasn't able to quite make the pitches that I wanted to. A lot of credit to them as a lineup."
The Astros had a chance to close it out in the ninth when Jeremy Pena whacked one to right field with Jose Altuve on second base, but Nick Castellanos hustled to the ball and sent the game to the extra inning with a brilliant sliding grab.
"How long did we have the lead for the game, 15 minutes? Sometimes that's all you need," said Castellanos, who recorded an RBI single and ran home along with Bryce Harper courtesy of an Alec Bohm double in the fourth inning.
"I knew that I was going to do everything I could not to let it drop."
Game 2 of the best-of-seven series is set for Saturday in Houston.
