NEW YORK • Gennady Golovkin earned a unanimous decision over Daniel Jacobs on Saturday to retain his middleweight belts but not before boxing's knockout king was taken the distance for the first time.

He was forced to go 12 rounds, as Jacobs gave the middleweight superstar all he could handle in front of a boisterous crowd of 19,000 at Madison Square Garden.

Golovkin retained his World Boxing Council and World Boxing Organisation belts as two of boxing's pre-eminent punchers put on an entertaining show.

"I couldn't destroy him," said Golovkin. "He is a very clean, very good fighter. It is my first test for 12 rounds."

Judges Don Trella and Steve Weisfeld both scored the fight 115-112 and Max DeLuca had it 114-113 for Golovkin.

Cancer survivor Jacobs was the underdog but he used his 4.5kg weight advantage and longer reach to his advantage and possibly provided the blueprint for Canelo Alvarez to use against the 34-year-old Kazakh in a future title fight.

Golovkin, who won 33 of his previous 36 fights by knockout, improved to 37-0. But his 23-fight knockout streak, which dated back to 2008, came to a halt.

Jacobs decided the extra weight in the ring was more important than fighting for all of Golovkin's titles and the gamble almost paid off.

The American dropped to 32-2, with 29 knockouts, after forfeiting the right to compete for Golovkin's International Boxing Federation belt when he missed the mandatory weigh-in on Saturday morning.

"At times I stood toe-to-toe with him to see what the power was like, what everybody was talking about, and it wasn't that bad," he said.

The 30-year-old added that he felt he won the fight but said the judges favoured the champion.

"Daniel Jacobs got X-ed out," he said. "I won the fight by at least two rounds. All I can do is be gracious about the decision."

On the undercard, Thailand's Srisaket Sor Rungvisai (42-4-1) captured the WBC super flyweight title with a stunning majority decision over unbeaten champion Roman Gonzalez (46-1).

AGENCE FRANCE-PRESSE, REUTERS