Joseph Parker beat Zhilei Zhang by majority decision to win the WBO interim heavyweight title in Riyadh, Saudi Arabia.
Zhang thought he had done enough after handing Parker two knockdowns in the 12-round fight.
The match between Parker and Zhang was the undercard before main event between Anthony Joshua and Francis Ngannou.
Parker, who beat American former WBC champion Deontay Wilder in Riyadh in December, picked himself up after a straight left in round three and came back from a left-right combination in the eighth.
The ringside judges scored the fight to Parker 113-113, 114-112 and 115-111.
“Thank you to my team. This is a great win. I feel like we’re on the up now. Zhang is a tough man, he knocked me down twice. I’m very happy and go home and celebrate,” Joseph Parker told Dazn Sport.
“Hard work, hard work. After the defeat to Joe Joyce and the win over Jack Massey, I still wasn’t happy with my performance. Now, look where we are.
“We are contracted to have a rematch so we will do it again.”
Britain’s Nick Ball and Mexico’s WBC featherweight champion Rey Vargas earlier fought a split-decision draw despite the challenger twice flooring the belt-holder.
