Jermell Charlo and Brian Castano were both denied a historic unification win when they drew their super-welterweight fight in San Antonio, Texas.
All four belts in the division were on the line for the first time, but Charlo retained the WBC, WBA and IBC titles and Castano his WBO belt.
Charlo almost knocked his opponent down but Castano controlled the tempo.
The judges called it 117-111 for Charlo, 114 apiece and 114-113 for Castano.
Both fighters disagreed with the result and claimed they deserved victory.
"A draw isn't what I wanted to hear," said Charlo, whose record now stands at 34-1 with 18 knockouts and one draw.
"I won this fight. I hurt him a lot more. My power is serious. I had him in trouble in the second and 10th rounds.
"This is my first time experiencing something like this. This comes with boxing - wins, losses and draws."
Castano, who is now 17-0 in his career with two draws and 12 knockouts, disagreed with Charlo's assessment.
"I won the fight. There were some rounds that he hit me hard, but I won the fight," he said.
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