Oleksandr Usyk just about did enough to win a majority points decision and a second world cruiserweight title on Saturday.
Usyk moved one fight away from becoming undisputed world cruiserweight champion after sustaining an unrelenting pace in a fight high in quality with Mairis Briedis.
The Ukrainian became WBO-WBC cruiserweight champion, thanks to scores of 115-113, 115-113 and 114-114 at the Arena Riga in Riga, Latvia.
Usyk relieved Briedis of his WBC belt in a second defense while also defending his WBO belt for the fourth time.
It was an enthralling encounter with great skills, great heart and great action from both champions, with little between to separate them. Both emerged from the fight with their reputations enhanced and the prospect that popular demand will see them fight again.
"Those are the most difficult rounds I've had in my career, and we will work on the improvement of my style," said Usyk, who also paid tribute to his beaten opponent.
It was not the result Briedis' home city fans wanted, but victory gives Usyk the opportunity to win the other two world cruiserweight titles in the final of the World Boxing Super Series (WBSS) in his next fight.
The Ukrainian will not have to wait long to learn his opponent in the WBSS final, as Russia's Murat Gassiev (25-0, 18 KOs) and Florida-based Cuban Yunier Dorticos (22-0, 21 KOs) will meet in the other semifinal at the Bolshoy Ice Dome on Feb. 3 in Sochi, Russia.
Usyk (14-0, 11 KOs), 31, will be ringside to see IBF champion Gassiev and WBA titleholder Dorticos fight for the right to face him in the final of the eight-man elimination tournament, scheduled for May in Saudi Arabia.
But Usyk, the tournament's No. 1 seed, had a difficult time of it in the opening two rounds. Usyk, who stopped Germany's Marco Huck in the 10th round of his quarterfinal in September, moved about the ring better, but it was Briedis (23-1, 18 KOs), 33, who was more accurate with his punches.
It was absorbing from the first bell, with both committed to all-out attack. Usyk landed a good right hook amid a combination in the second round, and the pair of them carried on slugging each other after the bell as, along with referee Kenny Bayless, they failed to hear the bell amid the noise created by Briedis' fans.
Usyk was cut above his right eye by an accidental head-butt in the third round, but the Ukrainian did not let it unsettle him and finished the round strongly.
The fourth belonged to Briedis', as he backed up Usyk for most of the session, but the Ukrainian had a big fifth, and the home hero ended the round with his face splattered in blood. Once again, Usyk finished the round strongly, as he caught Briedis flush with a left uppercut in a two-punch attack just before the bell.
It was breathtaking action in the sixth, swinging one way and the other. Briedis wrestled Usyk to the canvas in the sixth, but it was a rare, ugly moment in a superb bout.
In the seventh, Usyk caught Briedis with a left to the jaw as the Latvian looked disorganised for once in the fight. Briedis increasingly found himself on the back foot in the second half of the fight as well.
Briedis, a former policeman and the first Latvian to win a world boxing title, was on the retreat again in the eighth, and Usyk's southpaw jab found the target more.
Both stayed within striking distance of each other for nearly all of the fabulous fight, and neither looked to hold despite the unrelenting pace.
Usyk was on the front foot more in the latter rounds, but as he swarmed over Briedis in the ninth, he had to take a huge right uppercut.
It was hard to separate them, but Usyk smartly did a lot of his best work in the final moments of the rounds, just as he did in the 11th, which he ended by landing a left cross.
Briedis, who won the WBC title from Huck on points last April and then outpointed Cuba's Mike Perez in his quarterfinal, finished strongly by landing a series of big right hands amid a brilliant, see-saw last round. But it was not enough, and two judges scored the fight for Usyk by two rounds.