Tony Bellew outlasted Nathan Cleverly over 12 rounds to claim victory by a split decision to avenge his 2011 defeat to his cruiserweight rival in Liverpool.
Bellew, on home turf, finished the stronger after a tight opening eight rounds and though Cleverly prevail on one scorecard, the 31 year old prevailed 114-115, 116-112, 115-113.
"I'm over the moon, it's put to bed," said Bellew. "I've said a lot of things, I don't like him but I've outworked a great athlete and it's over.
"I'll fight anywhere, he's not a cruiserweight. It's been a long camp, 12 weeks, he was pacing himself and he looked at the belly and thought he would tire – I don't tire at cruiserweight."
Though the winner is expected to face WBO cruiserweight champion Marco Huck, calls for a deciding third fight are likely to intensify.
The 27-year-old Cleverley said: "I said it would be a replica of the first.
"A split decision shows my character, he was using his natural strength – maybe we'll have a third fight one day, this is the second time I've come to Liverpool, maybe we have a third fight in Wales."
Matchroom chief Eddie Hearn added: "It took time to catch fire, I felt Tony won the fight but fair play to Nathan. If there's a demand for the third we'll get it on. Marco Huck wants to fight Tony for the title, and so do a lot of other champs."
Elsewhere, on a jam-packed schedule at the Echo Arena, George Groves was forced to work before stopping Denis Douglin in the seventh round to remain on course for an all-British rematch with James DeGale.
Groves remains the mandatory challenger for Anthony Dirrell's WBC super middleweight title after flooring the American Douglin before referee Victory Loghlin stopped the fight moments later.
"Good to get another stoppage and it roll on the big one now," Groves said. "I want to take the quickest route to a World title and that's the Dirrell fight. I want to be a WC and bring a WT belt to Britain. I'll be a World Champion next year."
Anthony Joshua meanwhile produced the 10th straight knock-out victory of his short heavyweight career with a 90-second destruction of Michael Sprott and will face Kevin Johnson on 31 January in the next test of his growing reputation.