HOUSTON (AP) - A timely swing by J.T. Realmuto propelled the Philadelphia Phillies to an unlikely win in the World Series opener.

A terrific stab by right fielder Nick Castellanos gave him that shot.

Realmuto hit a solo home run in the 10th inning and the Phillies, saved by Castellanos’ sliding catch, rallied past the Houston Astros 6-5 Friday night.

Down 5-0 early against Astros ace Justin Verlander, the Phillies became the first team in 20 years to overcome a five-run deficit to win a World Series game.

They can thank Castellanos for getting the chance. Known much more for his bat than glove, he rushed in to make a game-saving grab on Jeremy Peña’s blooper with two outs in the ninth inning and a runner on second.

“All in all, it was a great game, a great come from behind victory, and it just showed the resilience of the club again and how tough they are and they just never quit,” Phillies manager Rob Thomson said.

Realmuto, who hit a tying, two-run double in the fifth off Verlander, completed the comeback when he led off the 10th by sending a fastball from Luis García into the seats.

Realmuto hoped for the best as he saw right fielder Kyle Tucker pursuing the ball.

"Once I saw him running back to the wall, I was thinking in my head, 'Oh, please just don’t catch it, just don’t catch it.’”

He didn't, the ball sailing just beyond his reach.

Realmuto circled the bases in a scene he dreamed about as a kid.

“Oh, absolutely. Yeah. Absolutely. I mean Wiffle Ball games in the backyard, the whole 3-2, bases-loaded, two-out situation. I probably had 7,000 at-bats in that situation growing up,” he said.

And did he usually deliver?

“Every time, yes,” Realmuto said, laughing.

Realmuto became the first catcher to hit an extra-inning home run in the World Series since Carlton Fisk waved his walk-off fair in the 12th inning of Game 6 in the 1975 Series against Cincinnati at Fenway Park.

Big-hitting Bryce Harper added two singles for the Phillies in his World Series debut. The two-time NL MVP is batting .426 (20 for 47) with five homers this postseason.

Tucker homered twice for the Astros, who had been 7-0 in this postseason.

“Disappointing, yeah, for sure,” Verlander said. “I need to do better. No excuses.”

Houston had a chance in the 10th when Alex Bregman doubled with one out. After Yuli Gurriel drew a two-out walk, David Robertson bounced a wild pitch that put runners on second and third.

Pinch-hitter Aledmys Díaz was then hit by a 2-0 pitch from David Robertson - but plate umpire James Hoye ruled that Díaz leaned into the pitch and didn't permit him to go to first to load the bases.

Díaz grounded out on a 3-1 pitch to end it.

The last team to blow a 5-0 lead in the World Series was the 2002 San Francisco Giants, who squandered their chance in Game 6 to close out the Angels and win the title under manager Dusty Baker.

Baker saw it happen again this time as manager of the Astros, by the same 6-5 final score.

The 106-win Astros hadn't lost to anyone since Philadelphia beat them on Oct. 3 behind Aaron Nola to clinch a wild-card spot as a third-place team and earn its first playoff trip in 11 years.

Houston raced out to a big lead thanks in large part to Tucker’s two homers. But the Phillies stormed back as Verlander again struggled in the World Series.

Perfect as he took a 5-0 lead into the fourth, he exited after the fifth with the score 5-all. That left him 0-6 with a 6.07 ERA in eight career World Series starts -- hardly the line for a pitcher who’s expected to soon pick up his third Cy Young Award.

The Astros fell to 0-5 in World Series openers and dropped their first game this postseason after sweeping in the AL Division Series and AL Championship Series.

Seranthony Domínguez pitched a scoreless ninth to get the win when Castellanos made his stellar play.

With Jose Altuve on second base after his two-out single and stolen base, Peña hit a ball that came off the bat at 68 mph and went only about 200 feet. Castellanos ran a long way, then with a lunge made the inning-ending catch while sliding to the ground.

Right before the pitch, Castellanos moved in a little closer.

“That was just what my instincts told me to do. I just thought he had a better chance of trying to bloop something in there than torching something over my head,” he said.

In the opener of the NL Division Series against Atlanta, Castellanos drove in three runs and helped preserve the lead with a somewhat similar catch in the ninth of that 7-6 win.

“I’ve had a couple people say that it seemed like a carbon copy of each other,” he said. “But I’m just happy that an out was made and we were able to go on and win both those games.”

In the World Series for the fourth time in six years - and after losing to Atlanta in six games last year - these Astros are looking to give Baker his first title as a manager and get their second championship after winning it in 2017, a title tainted by a sign-stealing scandal.

The surprising Phillies, who have two championships, are in the World Series for the first time since 2009. They bounced back from a 21-29 start that led to manager Joe Girardi’s firing.

Tucker had the orange-clad home crowd rocking early as he became the first player in franchise history with a multi-home run game in the World Series. One of the few players in the majors to hit without batting gloves and suddenly exuding attitude, he had four RBIs a year after finishing the Fall Classic without one.

The normally mild-mannered Tucker punctuated his first homer with a nifty bat flip and mixed in an expletive as he screamed toward the dugout while beginning his trot.

Nola took a perfect game into the seventh inning in his last trip to Minute Maid Park, more than three weeks ago when Philadelphia secured its first playoff spot since 2011. Things didn’t go nearly as smooth in his return Friday.

Tucker sent an off-speed pitch from Nola soaring high and into the seats in right field to put Houston up 1-0 with no outs in the second. Gurriel, Chas McCormick and Martín Maldonado added singles for another run.

Peña, the ALCS MVP, doubled to open Houston’s third before Yordan Alvarez grounded out. He was initially ruled safe, but the Phillies challenged the call, and it was overturned.

Bregman, who was Nola's roommate at LSU, walked before Tucker went deep again, knocking a ball into the stands behind the bullpen in right-center to extend it to 5-0.

Verlander, who had an MLB-best 1.75 ERA in the regular season, allowed six hits and five runs in five innings. He joined Roger Clemens as the only pitchers in major league history to make a World Series start in three different decades but still could not claim that elusive World Series win. Friday was his 12th career start in a postseason series opener, tying him with Jon Lester for most in MLB history.

Verlander, who started his third Series opener, retired the first 10 batters before Rhys Hoskins singled with one out in the fourth. Harper and Castellanos singled for a run and Alec Bohm hit a two-run double to cut the lead to 5-3.

Brandon Marsh opened the fifth with a double before Kyle Schwarber walked. Realmuto sent them both home with a double off the wall in left-center to tie it at 5-all.