Gennady Golovkin beat Sergiy Derevyanchenko by unanimous decision to reclaim the vacant IBF middleweight title at Madison Square Garden.
Kazakh Golovkin, 37, was fighting for just the second time since losing to Saul Alvarez in Las Vegas in September 2018.
He knocked down the Ukrainian in round one and cut him in round two but the rest of the fight became a slog.
Judges awarded the fight to Golovkin 114-113, 115-112, 115-112.
Golovkin was stripped of the IBF title last year for refusing to make a mandatory defence against Derevyanchenko, 33.
He opted instead for a rematch with Alvarez – which ended with Golovkin suffering the first defeat of his career.