BOSTON — Gerrit Cole struggled at the beginning of his second playoff start with the Houston Astros.

By the time he recovered, it was too late. Boston was well on its way to a big win.

Cole’s electric fastball was lined all over Fenway Park and he also committed a costly error in his first career appearance in the AL Championship Series, losing 7-5 to the Red Sox in Game 2 on Sunday.

“You know early, I thought he was a little over-amped,” Astros manager A.J. Hinch said. “He was pretty excited — a lot of energy, wasn’t [executing] a ton of pitches.”

One night after Justin Verlander pitched Houston to a 7-2 victory in the series opener, Cole was unable to duplicate the success of his fellow hard-throwing right-hander. The 28-year-old Cole allowed a season-high five runs and surrendered six hits — all of them on fastballs — in six innings.

Game 3 is tonight in Houston.

Cole said his main trouble in the first inning was his inability to get his breaking pitches over the plate.

“I was just not able to really find the zone with it and be able to put pressure on them with those offerings,” he said. “You know, I just found myself without leverage and I found myself with traffic, and I had to make some pitches. I did the best I could in those situations, but when you’re facing some of the best hitters in the world, they do their job as well.”

Cole went 15-5 with a 2.88 ERA in his first season with Houston after he was acquired in a trade with Pittsburgh, helping the World Series champion Astros return to the playoffs with a second straight AL West title.

He was terrific in the AL Division Series against Cleveland, striking out 12 while pitching seven innings of one-run ball in a 3-1 victory in Game 2. He joined Hall of Famer Tom Seaver as the only players to strike out at least 12 without walking a batter in the postseason.

He had a completely different performance against the high-scoring Red Sox.

Looking amped and jittery, Cole allowed his first run on his sixth pitch of the game. Mookie Betts drove his 3-1 pitch off the wall in center, and Andrew Benintendi followed with an RBI single.

After J.D. Martinez lined to second, Cole picked up Xander Bogaerts’ bouncer in front of the mound and threw wildly to first for an error. The miscue helped set up Rafael Devers’ RBI single.

“I fielded the ball, I checked second,” Cole said. “I felt like I had good footing to throw to Yuli [Gurriel] and the back foot gave out as I was throwing it and I just kind of goosed it.”

Houston tried to pick up Cole with two runs in the second and third, but he was unable to hold onto the 4-2 lead.

Jackie Bradley Jr. put Boston ahead to stay with a three-run double off the Green Monster with two out in the third. Cole walked Devers on four pitches and struck out Ian Kinsler swinging before Bradley’s big blow.

“I was having a little bit of trouble that inning trying to field my way through the strike zone,” Cole said. “I felt that after I had got the count back to 2-1 that I was going to just try to execute a fastball down and away. I executed it down, but it creeped over the plate too much which I guess gave him enough barrel to be able to just put it right on the wall down there.”

After Boston took its 5-4 lead, Cole struck out Christian Vazquez to end the inning and retired his next nine batters before he was lifted from just his third career start at Fenway.

Cole was 2-2 with a 3.13 ERA in four career playoff starts coming into the night.