LONDON — Britain treasures tradition, and the New York Yankees wrapped up the first trip to Europe by major league teams with one of baseball’s classic customs: a late-inning pinstriped comeback Sunday.

Gary Sanchez hit a go-ahead, two-run single in a nine-run seventh, and the Yankees overcome a four-run deficit to beat the Boston Red Sox 12-8 for a two-game sweep of the groundbreaking, high-scoring trek across the pond.

“It was a pretty cool experience,” Yankees right fielder Aaron Judge said.

DJ LeMahieu doubled off Marcus Walden (6-1) leading off the seventh and hit a two-run double against Josh Taylor later in the inning as the Yankees opened an 11-4 lead, sending 14 batters to the plate in their highest-scoring inning in four years.

“The energy never let up,” Yankees Manager Aaron Boone said. “It felt like a huge event, these two games.”

Boston and New York combined for 50 runs in the whacky games, four more than in any previous consecutive matchups of the rivals. The batters totaled 65 hits, 15 doubles and 10 homers over 18 innings that took 9 hours, 6 minutes to play out at Olympic Stadium.

While “Sweet Caroline” in the eighth inning brought the atmosphere of Fenway Park, the final out triggered the playing of “New York, New York,” making it seem like a summer night in the Bronx. The games at the home of the soccer club West Ham drew 118,718, a mix mostly of Americans who flew over and Britons.

“Like I was telling the guys yesterday, it felt like a soccer match at the end, so it was pretty cool,” said Yankees shortstop Didi Gregorius, who went deep against Ryan Brasier in the eighth and extended New York’s record streak of games with home runs to 31.

New York won the opener 17-13 after taking an 11-run lead and the finale after going ahead 12-4. Zack Britton ruled Britannia both days, escaping eighth-inning trouble with the tying run at the plate. New York relied on an Old Chap – Aroldis Chapman – who closed out each game and struck out the final three batters Sunday.

“I did not think I would pitch in both games, winning by that many runs,” Chapman said through a translator.

Built for the 2012 Olympics, the stadium was designed for minimal wind, leading to speculation that might have been a factor in pitchers’ difficulty locating breaking balls. The temperature dropped to a more normal 73 degrees at first pitch – 20 below Saturday’s scorcher.

Shadows, glare, white seats and a swift turf left every lead perilous as a 16th-century trip to the Tower of London.

“The ball flies. The ground balls, too,” said Luis Cessa, who pitched shutout ball from the second through the fifth for New York.

Before a sellout crowd of 59,059, the Red Sox began brightly in their alternate red jerseys. Xander Bogaerts, J.D. Martinez and Christian Vazquez hit home runs in the first inning, opening a 4-0 lead against Stephen Tarpley, who was making his first big league start.

But in a game that took 4:24, Boston dropped a season-high 11 games behind the AL East-leading Yankees (54-28), who won for the 13th time in 14 games overall and improved to 6-1 against the Red Sox this year.

“Right now they’re a lot better than us, and we need to get better,” Red Sox Manager Alex Cora said. “Last year we were putting teams away. This year we’re not doing that. … It’s not a lack of effort. I think it’s lack of execution.”

Boston’s bullpen blew a save for the 17th time, second only to the New York Mets’ 21.

New York pulled within 4-2 in the second on Gio Urshela’s RBI groundout and Brett Gardner’s run-scoring single. Eduardo Rodriguez and Colten Brewer maintained the lead through six innings, but Walden allowed all four batters he faced to reach in the seventh: LeMahieu doubled, Judge walked, Aaron Hicks hit an RBI double and Sanchez singled for a 5-4 lead.

Urshela hit a two-run single off Matt Barnes, LeMahieu’s second double boosted the lead to 9-4, Hicks had a sacrifice fly and Sanchez hit a grounder that bounced off the glove of Michael Chavis at first for a run-scoring error.

“I don’t think we’re pressing. For me right now it’s just missing location with the slider,” Walden said.

Adam Ottavino (3-2) got the win. After Boston rallied in the eighth on Vazquez’s two-run single off Chance Adams, Eduardo Nunez’s RBI double and Sam Travis’ run-scoring single against Britton, Rafael Devers left the bases loaded by grounding out.

For me, this means a lot being back in Europe,” said Gregorius, who was born in Amsterdam. “It’s fun being here. It’s always a crazy atmosphere.”

LOOKING AHEAD

The Yankees open next season at Baltimore on March 26 to start a three-game series, play three more at Tampa Bay and face Toronto in their home opener April 2, according to details from baseball’s draft schedule that was obtained by The Associated Press.

They host Boston from May 8-10, July 24-26 and Sept. 8-10, and play at Fenway Park from June 12-14, July 30-Aug. 2 and Aug. 31-Sept. 2. The Yankees host the Mets on July 7-8 and are at Citi Field on July 28-29.

MISTAKE

New York GM Brian Cashman said it was a mistake to have right-hander Luis Severino start his throwing program without having an MRI. Severino stopped throwing last week after feeling soreness and then had an MRI, which showed his strained late muscle was only 90 percent healed. Cashman said Severino is reluctant to have MRIs because he isn’t comfortable going into the tube for the scan.

OLD TIMES

Boston had not homered three times in the opening inning since Aug. 14, 1979, when Carl Yastrzemski, Carlton Fisk and Fred Lynn did it at Fenway Park off Pete Redfern of Minnesota.

TRAINER’S ROOM

Yankees: Sanchez came out after jamming his left thumb while catching a pitch in the eighth. … First baseman Luke Voit didn’t play after injuring his left abdomen Saturday.

Red Sox: Left fielder Andrew Benintendi didn’t start because of leg problems.

UP NEXT

Yankees: Left-handers James Paxton or J.A. Happ could start Tuesday night at the crosstown Mets.

Red Sox: Left-hander David Price (5-2) will start Tuesday night’s series opener at Toronto, which goes with right-hander Trent Thornton (2-5).