Billy Joe Saunders beat Andy Lee by a majority verdict to become the new WBO middleweight champion and stretch his unbeaten record to 23 fights.
Englishman Saunders twice knocked down Lee in the third round, but the reigning champion recovered and the fight descended into a cagey affair.
Lee, who had only been beaten once before in his career, regained his composure as the bout wore on, but the gap in the judges' minds was too big to overturn.
One judge did score the bout a 113-113 tie, however the third round made all the difference in the end as the other scorecards came in at 114-112 and 115-111.
The fight's defining moment came as 31-year-old Lee was twice floored by right hands from Saunders.
Credit to the Irishman, who recovered to pressurise his opponent, and a late flurry gave him some encouragement that he may have salvaged a draw, but it was not to be.
"[Saunders] kept his composure. I was worried his heart would rule his head, but he wasn't rushing in," promoter Frank Warren told BoxNation.
"He was surprised that one judge had it a draw. It's been a great journey. If Chris [Eubank Jr.] wants that fight, we can do it in a heartbeat."
On the undercard, Liam Smith succesfully defended the WBO super-welterweight title against his first challenger, stopping Jimmy Kelly in seven rounds.
Paul Butler, meanwhile, recorded a sixth-round stoppage of Romania's Silvio Olteanu.