Liam Williams lost his WBO world middleweight challenge against Demetrius Andrade by a unanimous points decision in Hollywood.
It was a nightmare start for the Welshman who hit the canvas in round two, but took the fight the distance.
The undefeated American used his experience and fought in eye-catching bursts, while Williams struggled to land his shots.
The judges scored the bout 118-109, 118-109 and 116-111.
There had been bad blood in the build-up to the main event, with 33-year-old Andrade unimpressed with the calibre of his mandatory opponent.
Williams, 28, had twice lost to Liam Smith in 2017 before notching up seven successive wins to earn his shot at the title.
Andrade showed little respect, but as the final bell rang at the Seminole Hard Rock Hotel & Casino, he certainly knew he had been in a fight.
Andrade, who now has a perfect record of 30 victories with no defeats, came out with serious intent and it looked like it was to be a short night's work.
He showed speed, power and accuracy, with Williams doing well to survive the first round after taking some heavy shots.
As he began to regain some composure in the second, Williams was floored by a right-left combination which saw him take every available second of the count to steady himself.
To Williams' credit, he kept chipping away and the champion looked tired at times, especially in the ninth as he clung on to see out the round.
But Williams, who was bidding to become Wales' 13th world boxing champion, could not make him pay, and was left to rue his inaccuracy as he ran out of time.