Former unified middleweight champion Gennady Golovkin insisted he is "ready" for a rematch with Saul 'Canelo' Alvarez after making a devastating return to the ring in New York.

Fighting for the first time since losing his belts to Canelo in September last year, Golovkin knocked out the previously undefeated Steve Rolls in the fourth round on Saturday.

Golovkin showcased his devastating power at Madison Square Garden, where the Kazakh star floored Rolls (19-1, 10 KOs) in brutal fashion.

"I feel great," Golovkin told DAZN after kicking off his six-fight, three-year deal with the streaming service. "I feel like a new baby.

"Right now I feel completely different because I came back to my knockout. I love knockouts and I love New York. It was a great night all around."

Saturday ended a nine-month layoff for Golovkin (39-1-1, 35 KOs), who lost to Canelo in a gripping majority decision – his only professional defeat.

Golovkin lost his WBA and WBC titles after the pair's initial bout in September 2017 ended in a hotly disputed draw.

Asked who he wants next, Golovkin was emphatic in his response ahead of a potential GGG-Canelo trilogy.

"Everybody knows. The fans know who they want me to fight next," Golovkin said. "I'm ready for September. I'm ready for Canelo. Just bring him, just ask him. I'm ready. If you want big drama show, please tell him. I'm ready to bring back the big drama show."

"I believe, because this is boxing. This is boxing business. Why not? The next fight will be amazing for us," Golovkin added.

"I feel right now like the people's champ. It doesn't matter for me. I want to beat him but [the belts don't] matter. I'm the people's champion."