Anthony Joshua needed a knockout.

Entering the final round of his heavyweight title defense against Oleksandr Usyk, Joshua, a power-punching 31-year-old from London, and one of boxing’s largest global stars, trailed on the judges’ scorecards, losing rounds early to a smaller, craftier challenger. When the bell sounded, he pressed forward.

But Usyk closed the show.

Usyk, an undefeated 34-year-old from Ukraine, landed a left and right early, quieting the crowd at a sold-out Tottenham Hotspur Stadium in London. Late in the 12th, Usyk wobbled Joshua with a left hand, and a two-handed flurry of punches sent Joshua to the ropes as the final bell approached.

That emphatic last round carried Usyk to a unanimous decision win in a fight most observers expected him to lose. The judges scored the bout 117-112, 116-112, and 115-113, all for Usyk.

The outcome quieted the roughly 70,000 spectators present, most of whom supported Joshua by singing in unison through the early rounds. But it didn’t surprise Usyk, a former undisputed cruiserweight champion who moved up to heavyweight in 2019.

“The fight went exactly the way I expected it to go,” said Usyk, who is now 19-0. “There were a couple of moments where Anthony pushed me, but nothing special.”

Joshua entered the bout with natural advantages in size — he stands 6-foot-6, compared with 6-foot-3 for Usyk, and at 240 pounds he outweighed the challenger by more than 18 pounds. He also held heavyweight championships from four different boxing governing bodies: the World Boxing Association, the World Boxing Organization, the International Boxing Federation, and the International Boxing Organization.

But Usyk, a calculating southpaw, showed up with superior footwork and won the first three rounds by finding the best angles and then landing punches: A straight left that grabbed Joshua’s attention in Round 1; a left to the head that buckled Joshua’s knees in the third. Usyk said his early success tempted him to apply more pressure, but then he remembered his game plan.

“In the beginning I hit him hard and tried to knock him out,” Usyk said. “But then my trainers said stop and do your job.”

Joshua won rounds mid-fight by relying on his jab and body punching, dialing back his power to increase his accuracy, and wearing Usyk down. By the 10th, Usyk had red marks under each eye, and a divot in his right eyebrow. Joshua’s right eye had also swollen, making him an easier target for Usyk’s overhand lefts.

Leading up to the fight, Joshua and his backers framed the event as a celebration — the first stadium show and most-attended boxing event in England since the coronavirus pandemic began. They also presented it as a sort of formality. Joshua faced Usyk only because the World Boxing Organization mandated the fight, and Joshua and his promoters at Matchroom Boxing spoke openly about matching with the winner between Tyson Fury and Deontay Wilder, who are scheduled to fight Oct. 9.

A heavyweight megafight would have made financial sense. Joshua attracts a massive audience. His Instagram account boasts 12.9 million followers, and his title-winning triumph over Vladimir Klitschko drew 90,000 spectators to London’s Wembley Stadium in April of 2017.

Instead, Usyk and Joshua provided another example of how quickly the heavyweight landscape can change.

In mid-May, Hearn and Fury each announced an agreement for a midsummer title unification bout between Fury and Joshua in Saudi Arabia. But days after that deal went public, an arbitrator in the United States ordered Fury to face Wilder, who had invoked his rematch clause after losing to Fury in February 2020, and had filed suit to enforce it.

That legal decision torpedoed Joshua-Fury, and led to Joshua’s bout with Usyk, which ended in an upset that will have promoters recalibrating plans.

Moments after the bout, Eddie Hearn, Joshua’s promoter, said the now former champion would likely exercise his contractual right to an immediate rematch.

“For me, he’ll go straight into the rematch,” Hearn said. “But he’ll have to bring something different.”

But Usyk told an in-ring interviewer that he hadn’t seen his children in months, and that he needed family time.

“I’m not thinking about the rematch at the moment,” he said.