Josh Taylor lost his unbeaten record and his WBO super-lightweight title as he was outpointed by Teofimo Lopez at Madison Square Garden in New York.
The Scot started well but Lopez took control of the fight in the middle stages and the finished strongly, with the scorecards reading 115-113, 115-113, 117-111 in favour of the American.
Lopez becomes a two-weight world champion.
Taylor, who suffered a first defeat in 20 professional bouts, was magnanimous in defeat, telling Sky Sports: "No excuses. He was better on the night. It is what it is so congratulations to Teofimo.
"I would love to do it again. I know I am better than that and I know I can beat him.
"So yes, I would love to do it again but he’s the champ and the ball is in his court."
Lopez said: "I just want to thank God first. It has been a long time coming.
"We just beat the number one champion, Josh Taylor, former undisputed champion."
