BOSTON -- Confidence filled Giancarlo Stanton as he swung a bat in Fenway Park’s on-deck circle, watching a left-handed reliever pop warmup tosses over home plate. The Red Sox were gambling that Darwinzon Hernandez would retire the left-handed Anthony Rizzo, thus avoiding a looming mismatch for the ages.

Stanton’s thoughts in that moment: “They’d better get Rizz out.”

They did not. Rizzo was hit by a pitch and Stanton pounced on a meaty fastball, clearing the Green Monster for a go-ahead grand slam on Saturday. Stanton’s eighth-inning Lansdowne Street souvenir powered New York’s come-from-behind 5-3 victory over the Red Sox.

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"It’s a great feeling,” Stanton said. “There were a lot of emotions going on. I’m just glad I was able to do it, compress everything and be on time for the fastball. Something good happened.”

The Yankees (88-67) have won five consecutive games to tie the Red Sox (88-67) for the top spot in the American League Wild Card chase with seven games remaining, although Boston would host the WC Game if the teams finish tied by virtue of the better head-to-head record. Toronto won, 6-1, to remain 2 games back of both teams.

“We love it right now,” manager Aaron Boone said. “Tomorrow becomes really important. That’s how we look at it. Whether we win all these games or lose a game along the way, we’ve just got to live in the moment and relish the moment. I think our guys love being in this environment with a lot on the line.”

Stanton was the perfect man for the spot, now having crushed 17 home runs since Aug. 1 to surpass Aaron Judge for the team’s RBI lead with 91. The Yankees’ bench exploded in ecstasy, though to hear Luis Severino tell it, they could see Stanton’s big blast coming.

“That’s not the first time he’s been in a big situation and came through,” Severino said. “I could feel it, that he was going to go up there and make a good swing.”

Not much had gone the Yankees’ way to that point; held to one run on three hits over 5 1/3 innings by starter Nick Pivetta, the Yanks had a runner cut down at home plate in the sixth and flushed a promising opportunity in the seventh.

Their fortunes turned in the eighth. Facing Tanner Houck, Brett Gardner worked a six-pitch walk with two outs and stole second base ahead of a free pass to Judge. Hernandez plunked Rizzo in the right knee, then grooved a 94.3 mph first-pitch fastball that Stanton pummeled for a Statcast-projected 452-foot slam; Boone described it as “electric.”

“There were a lot of great at-bats, winning at-bats, to set that situation up,” Boone said. “The inning hinges on, ‘Come on and get on, Rizz.’ If Rizz can work his way on, Giancarlo coming up with the bases loaded pops into your head. For him to go up and stick it on that first one, he didn’t waste any time.”

It was the ninth career grand slam and second of the season for Stanton, who became the first Yankee since Johnny Blanchard in 1961 to hit a go-ahead grand slam in the eighth inning or later at Fenway Park.

“We were talking about it in the dugout; we had the right guy up,” said Yankees starter Néstor Cortes Jr. “He’s been hot lately. You wouldn’t want anybody better at this point. As soon as he was on second base, he looked at us and we just gave him a flex. It was awesome.”

Cortes limited Boston to two runs on four hits over 4 1/3 innings, retiring the first seven Sox before Kevin Plawecki hit a solo homer that struck a light tower over the Green Monster in left field.

Severino picked up the victory in relief, striking out four over two scoreless innings. He showcased his fastball, slider and changeup in the outing, and has pitched four scoreless frames over two appearances since returning from the injured list earlier this week.

“I really don’t like the bullpen,” said Severino, who was credited with his first win as a reliever since Sept. 20, 2016, at Tampa Bay. “I’m a starter; I love starting. But right now, it’s the situation. The bullpen all year long has been the key for this team. Being there with those guys and trying to help the team, I think that’s big.”

Aroldis Chapman worked around a Bobby Dalbec homer and a hit batsman in the ninth to record his 29th save, setting up a chance for the Yanks to overtake their rivals with Sunday’s series finale.

“We’re now in a better situation than we were yesterday and the day before,” Stanton said. “It’s our job to get out of this city in an even better situation.”