NEW YORK — Fans packed Yankee Stadium and red, white and blue bunting was out on a sun-splashed afternoon, just like opening days before the pandemic.

Shadows had crawled across the infield by the time Josh Donaldson capped his New York debut with a performance reminiscent of the Yankees of old — their first walk-off win on opening day since Yogi Berra charged across the plate on Andy Carey’s single to beat the Washington Senators in 1957.

“The energy in the stadium, the atmosphere was pretty electric,” Donaldson said Friday after his 11th-inning single lifted the Yankees over the Boston Red Sox 6-5. “It doesn’t get any bigger than this right here.”

Donaldson, the 2015 AL MVP with Toronto, was acquired from Minnesota on March 13. He completed a comeback from a 3-0, first-inning deficit, becoming just the third Yankee with a walk-off RBI in his first game after Roy Weatherly in the 1943 opener and Chase Headley in July 2014, according the Elias Sports Bureau.

“It’s amazing for him to come and to get on the good side of this place right away,” teammate Giancarlo Stanton said.

Isiah Kiner-Falefa, also obtained in the Donaldson trade, started the inning as the automatic runner at second base in the first extra-inning game of the strange rule’s third season.

Donaldson hit a three-hopper up the middle against rookie Kutter Crawford leading off the 11th, just past the dives of new Boston second baseman Trevor Story and shortstop Jonathan Araúz, who took over in the 10th after Xander Bogaerts strained his right hamstring.

Kiner-Falefa slid across the plate well ahead of center fielder Kiké Hernández’s one-hop throw. Donaldson ran all the way to second and flipped his helmet, then was mobbed by teammates.

“Some people handle it really well, some people not as much,” Yankees manager Aaron Boone said. “There’s a level of wanting to ingratiate yourself to the new town, new people, new fans, teammates.”

It was the Yankees’ sixth walk-off win in an opener, the team’s first over Boston since 1906.

The Red Sox led 3-0 on Rafael Devers’ two-run homer and J.D. Martinez’s RBI double before Gerrit Cole got a single out, the Yankees ace out of sorts after a lengthy pregame ceremony disrupted his routine.

Seats were filled with a sellout crowd of 46,097, COVID-19 protocols were dropped and opening-day festivities returned after two seasons altered by the pandemic.

Ukraine’s flag was raised and its national anthem played before “The Star-Spangled Banner” during ceremonies that included a moment of silence for war victims.

“Festivities got a little away from the schedule,” Cole said.

Anthony Rizzo had a two-run drive in the bottom half and Stanton tied it at 3 with a leadoff homer in the fourth. Both were off Nathan Eovaldi, who beat Cole in last year’s AL wild-card game.

Alex Verdugo pushed Boston back ahead 4-3 with an RBI single in the sixth off Clay Holmes through a drawn-in infield, but DJ LeMahieu homered off Garrett Whitlock in the eighth.

Bogaerts’s third hit put the Red Sox ahead in the 10th, an RBI single against winner Michael King, the Yankees eighth pitcher.

Pinch-hitter Gleyber Torres, out of the starting lineup in favor of LeMahieu at second base, tied it in the bottom half with a sacrifice fly off Ryan Brasier.

“I’m sure today was a really tough day for him,” Boone said. “That’s a tough spot where you’re down 0-2, shadows, late, first at-bat of the season, everything on the line.”

JUDGE-MENT DAY

New York star Aaron Judge let his deadline pass for a long-term contract. Judge, who said he will not negotiate during the season, went 2 for 5, including a two-out double in the ninth off Hansel Robles. He was stranded when Stanton struck out for the fourth time.

STAN-TONIAN

Stanton has five opening-day homers, including four with the Yankees. He struck out in his four other at-bats. Eovaldi, who allowed three runs and five hits in five innings, didn’t give up his second home run last year until June 4.

START ME UP

Story played his first big league game at second base after 733 at shortstop and went 0 for 5 at the plate in his Red Sox debut.

“It’s intense and that’s fun,” Story sad. “That’s the kind of atmosphere you want to play in. Every pitch counts and that’s the way we’re taking it.”

HIZZONER

New New York City Mayor Eric Adams played catch with Yankees right-hander Luis Severino before the game.

MEMORIES

Boston is wearing black patches on its right sleeves with a white No. 2 in memory of Jerry Remy, whose last name is in red. The former player and broadcaster died Oct. 30 at age 68.

SIGNALLING

Yankees catcher Kyle Higashioka moved the new Pitch Com signaling device from a wrist to a shinguard.

TRAINER’S ROOM

Red Sox: Bogaerts on his hamstring: “Hopefully I come back tomorrow and I feel good and get ready to go.” … RHP Matt Barnes was not available because of back tightness.

Yankees: Rizzo was hit on the right hand by a fastball from Eovaldi in the fifth inning that tailed in. He stayed in the game.

UP NEXT

Severino and Boston RHP Nick Pivetta are to start Saturday.