NEW YORK – Francisco Cervelli settled under Mike Lowell’s second-inning pop fly, a routine play that major league catchers make 99 out of 100 times, maybe even more.

This time the ball kicked off his glove and rolled into foul territory for an error. Three unearned runs later, the Boston Red Sox and Clay Buchholz had a two-run lead.

They never lost it Friday night in a 6-3 victory against the New York Yankees, the opener of a potentially pivotal four-game series.

“It’s pretty big, yeah. Everyone has high hopes going into (today),” Buchholz said. “We lose this one and then lose that one, everyone knows where that goes.”

David Ortiz hit his 24th home run of the season and rookie Ryan Kalish hit the first of his big-league career. The Red Sox closed to 5-4 in the season series and pulled within five games of the AL East-leading Yankees, who remained a half-game ahead of second-place Tampa Bay.

“We have to keep on winning, have to keep winning games,” Ortiz said. “Everything else takes care of itself.”

Lance Berkman, a new Yankee, thinks strong starters give the Red Sox a chance to compete for a playoff berth.

“When you have good pitching, it really doesn’t matter. You can put eight stiffs out there,” Berkman said, before quickly adding: “I’m not saying that’s what they have.”

Buchholz (12-5) allowed Mark Teixeira’s two-run homer in the first, then settled down to win for only the second time in five starts since June 20. He gave up three runs and nine hits in 71/3 innings, leaving his ERA at 2.66.

Cervelli blamed himself for the mistake.

“I think I moved my glove late and it dropped,” Cervelli said. “You never let the pitcher catch a fly ball. That’s my fault.”

Pitcher Javier Vazquez faulted himself. The ball was in front of him and he had a better angle.

“After he dropped it I said, ‘Man, I should have called that ball because it was an easy play for me,’ ” he said.

New York led 2-1 at the time. Walks to Jed Lowrie and Jacoby Ellsbury forced in the tying run, and Marco Scutaro lined a two-run, two-out double to left.

“Someone’s got to catch it. That’s the bottom line,” Yankees Manager Joe Girardi said following his team’s fourth loss in five games.

A crowd of 49,555 was the largest regular-season attendance at the new Yankee Stadium and the seventh sellout of the year, matching 2009’s regular-season total.

Derek Jeter singled in the first for his 2,873rd hit, tying Babe Ruth for 39th place. Jeter worked out a 12-pitch walk against Jonathan Papelbon with two outs in the ninth before Nick Swisher flied to left, giving Papelbon his 27th save in 32 chances.