Wales' Nathan Cleverly retained his WBO light-heavyweight title with a hard-fought points victory over Tony Bellew in Liverpool.
The challenger started fast but the 24-year-old champion found a rhythm by the middle rounds and had a lot of success with left hooks and upper-cuts.
But Bellew found a second wind and hurt Cleverly with some big right hands as the fight developed into a humdinger.
The attritional nature of the fight made it difficult to score.
One judge called it a draw, while two awarded it to Cleverly by wide margins.
However, the scorecards could not disguise what was without doubt Cleverly's toughest day at the office - he is now undefeated in 23 pro fights - and a rematch could be in the offing.
Cleverly was hoping for an eye-catching performance to set up a possible unification match with 46-year-old American veteran Bernard Hopkins, but the WBC title-holder lost his belt to Chad Dawson in Los Angeles in the early hours of Sunday morning, UK time.
In Liverpool, an ill-tempered build-up to the fight culminated in a flare-up at Friday's weigh-in and Cleverly was given a hostile reception by a partisan crowd at the Echo Arena.
And the first round was more of the same, with Cleverly steaming out of his corner on the sound of the opening bell before Bellew was given a stern ticking off by referee Richie Davies for what was deemed a deliberate headbutt.
Bellew, the British and Commonwealth champion, had Cleverly in trouble in round two with a chopping right hand but the champion settled in behind his jab in the third and was landing with the cleaner shots in the middle rounds.
Cleverly landed with a low blow in round five, which Bellew had to walk off, and by round six the challenger appeared to be running out of steam as Cleverly peppered his body with hurtful left hooks.
Round seven followed a similar pattern, Cleverly piercing his rival's defence with crisp hooks and upper-cuts, but Bellew soaked up the punishment and had a restorative eighth round.
Cleverly took a rest in round nine and in the following round Bellew landed with a crunching right cross that had Cleverly, who was fighting on the back foot by this stage, leaning on the ropes and swinging wildly.
But Cleverly, clearly aware he might need a strong final round in order to win a decision, finished the fight on the front foot, although Bellew was still giving as good as he got until the bitter end.
While the bout was tricky in terms of scoring, the lop-sided scorecards of two of the judges betrayed just how competitive the bout had been - indeed, it was a genuine contender for fight of the year, with Bellew playing his part in the proceedings.
A devastated Bellew, who drops to 16 wins and one defeat, will now target a tilt at the European title - unless Cleverly denies him an immediate rematch - while Cleverly will target a unification match early next year.