It seemed like deja vu all over again.

For the sixth time in seven games to start the second half, the Red Sox bullpen blew a lead in the seventh inning or later. This time the collapse was particularly noisy, as Zack Kelly allowed back-to-back home runs — including a 470-foot three-run moonshot by Aaron Judge — to turn a one-run lead into a three-run deficit in the bottom of the seventh.

But then what could have been the latest in a string of ugly losses turned into perhaps the defining win of the Red Sox season so far.

After falling behind late the Red Sox rallied for five unanswered runs over the last three innings to stun the New York Yankees 9-7 in Friday’s series opener. Wilyer Abreu tied the game with a pinch hit RBI double in the bottom of the eighth, and Masataka Yoshida came through with the go-ahead two-run single to put Boston ahead for good.

Kenley Jansen then came on and pitched a scoreless ninth, including a strikeout of Judge, to pick up his 20th save of the season.

Before the late-inning theatrics, things started off encouragingly enough for the Red Sox, who overcame their struggles against left-handed starting pitchers by making Yankees lefty Nestor Cortes’ evening a nightmare. Right from the beginning the Red Sox put pressure on Cortes, who allowed four runs and 13 total baserunners over his 4.2 innings of work.

Boston loaded the bases in the first and took an early 1-0 lead on a Tyler O’Neill sacrifice fly, scored again on a Rafael Devers RBI single in the third, got an RBI double from lefty-killer Rob Refsnyder in the fourth and finally another sacrifice fly from Masataka Yoshida in the fifth.

Despite all that traffic, the Red Sox also let a lot of golden opportunities slip by the wayside. They collectively went 2 for 8 with runners in scoring position and stranded eight men on base through the first five innings, including men at second and third in the bottom of the fifth when reliever Tyler Kahnle struck out Jamie Westbrook to clean up Cortes’ last mess.

Meanwhile, Brayan Bello continued struggling with his command.

Usually dominant against the Yankees, Bello’s pitch count ballooned early and he allowed New York to come from behind and tie the score twice. He allowed a solo home run to Anthony Volpe in the second that knotted the game at 1-1, and in the fifth he allowed three straight hits to start the inning, including an RBI double by Trent Grisham, before serving up a game-tying sacrifice fly to Alex Verdugo.

Bello ultimately went five innings and allowed three runs on five hits and two walks while striking out four. He threw 80 pitches, only 47 for strikes.

Still, the last run against Cortes in the bottom of the fifth put the Red Sox back ahead 4-3, and for a little while it looked like that might be enough.

The Red Sox denied New York a tantalizing scoring opportunity in the sixth when shortstop Ceddanne Rafaela made an incredible throw home on an infield grounder to gun down Austin Wells at the plate. That helped Cam Booser and Josh Winckowski combine for a scoreless inning, but in the bottom of the sixth the Red Sox stranded two more runners, and then all hell broke loose in the top of the seventh.

Brennan Bernardino came on to start and allowed a single, drew a lineout and then walked Juan Soto to put two on with Judge coming to the plate. Alex Cora then summoned the right-hander Kelly to face Judge, who sent the first pitch he saw into the stratosphere for the go-ahead three-run bomb.

Austin Wells added insult to injury moments later with his solo shot to right, which sent Tyler O’Neill tumbling over the short wall in right field trying to catch. O’Neill was ok, but the damage was done as the Red Sox suddenly found themselves looking up at a 7-4 deficit.

From there, the comeback was on.

Boston answered New York’s haymaker with a big shot of its own in the bottom of the seventh, when Ceddanne Rafaela clobbered a Luke Weaver fastball over the Green Monster for a two-run shot. Then after Bailey Horn kept the Yankees off the board with a scoreless eighth, Rob Refsnyder singled and Connor Wong drew a 10-pitch walk to put two men on with nobody out in the bottom of the frame, bringing Rafael Devers to the plate.

Weaver was able to stave off the big hit by getting Devers to fly out to left, but then Yankees manager Aaron Boone summoned his closer Clay Holmes, and the embattled All-Star couldn’t get the job done.

With the win Boston improves to 55-47 and now trails the Yankees (60-45) by just 3.5 games in the AL East standings. The two rivals will face off again on Saturday, with first pitch scheduled for 7:15 p.m.