BOSTON — The Houston Astros patiently waited out Rick Porcello through seven scoreless innings, then pounced when the Red Sox right-hander delivered a pair of mistakes.

Jake Marisnick led off the eighth with a double and George Springer drove the very next pitch from Porcello out for his AL-leading 17th homer as Houston won 3-1 on Friday night.

The Astros trailed Porcello and the Red Sox 1-0 entering the eighth, when Marisnick doubled to left on a 1-1 slider. Springer was ready when Porcello threw a high changeup, belting it over Boston’s bullpen in right-center.

“We were on our game for seven innings and then I messed up on two pitches and they capitalized on it,” Porcello said. “It’s a heck of a job on their part and I’ve got to get better late in the game.”

The Astros improved to 12-3 this month and matched the 2017 World Series championship team for the best start in franchise history at 30-15.

Will Harris (1-0) got the win with one scoreless inning of relief. Roberto Osuna picked up his 11th save, getting Mookie Betts to fly out to right with two runners on to end it. Boston went 1 for 11 with runners in scoring position and stranded 11.

Boston manager Alex Cora said it was his call to leave in Porcello, who had thrown 91 pitches through seven, and accepted the blame for the result.

“He doesn’t deserve to lose that game,” Cora said. “The way he moved the fastball, changed speeds, everything he did was outstanding. That’s the best lineup in baseball and he went seven scoreless.”

“Impressive win,” Astros manager A.J. Hinch said. “Our pitching did really well to hang in there all the way to that last out. It was pretty exciting.”

The Astros continued their torrid month of May with their ninth straight victory and got a perfect eighth inning from right-handed reliever Ryan Pressly, who set a record with his 39th consecutive scoreless appearance.

Houston won the opener of the three-game series between the last two World Series winners and a rematch of last year’s ALCS, which Boston won in five games.

Christian Vazquez went 3 for 4 with a pair of doubles and an RBI for Boston, which entered the game second to only Houston for the best record in May at 10-3.

Porcello was replaced by Ryan Brasier, who allowed an unearned run after walking Michael Brantley and running into some defensive problems. Brantley took second on a passed ball and third on a wild pitch before scoring on Josh Reddick’s sacrifice fly to right.