Gennady Golovkin said his controversial draw with Saul 'Canelo' Alvarez in the world middleweight title fight on Saturday was "bad for the sport".
After a closely fought bout in Las Vegas, one judge scored it 118-110 for Alvarez, another 115-113 for Golovkin and the third a 114-114 draw.
Kazakh Golovkin, 35, retained his WBA, WBC and IBF titles and remains unbeaten in 38 fights.
"It's terrible, for me it's terrible. This is not correct," said Golovkin.
"I saw the computer, the total punches and I saw people's reaction."
Golovkin added that he "wants a rematch" and Alvarez also confirmed he would face Golovkin again if "that's what people want".
According to statistics, Golovkin landed more punches overall but judge Adalaide Byrd had Alvarez as a clear winner, Dave Moretti scored the bout for Golovkin and Dan Trella had the fighters level.
Byrd's scorecard has since received heavy criticism after she awarded Alvarez 10 of the 12 rounds and a portion of the crowd at the T-Mobile Arena booed when the decision was announced.
But Mexican Alvarez felt he had done enough to take the middleweight titles away from Golovkin.
He started and finished the fight the stronger, and also produced some of the more eye-catching shots.
"I didn't base it on the scorecard, I wasn't taking points round-by-round but what I am sure of at the end of the fight was that I won," said the 27-year-old.
"I have no doubt in my mind, I won the fight."
Alvarez's record now stands at 49 wins (34 KO), two draws and one defeat from 52 fights.