England's Billy Joe Saunders outpointed champion Andy Lee to secure the WBO middleweight title in Manchester.
Saunders floored the Irishman twice with right hooks in the third and Lee rarely employed his vaunted left cross.
Saunders, 26, Britain's 12th world champion, won by majority decision, the judges scoring it 115-111, 114-112 and 113-113 in the challenger's favour.
Liverpool's Liam Smith retained his WBO light-middleweight title earlier with a seventh-round stoppage of Jimmy Kelly.
Both Saunders and Lee have plenty of boxing pedigree, with 31-year-old Lee, a cousin of world heavyweight champion Tyson Fury, boxing for Ireland at the 2004 Olympics and Saunders competing for Great Britain at the 2008 Olympics.
Saunders looked the sharper of the two in the opening two rounds, establishing his right jab and landing with a couple of flashing right hooks.
After a cagey first six minutes, a fight broke out in the third, Lee landing with a straight left before Saunders dropped the Irishman with a sweetly timed right hook.
Lee was up at seven but down again shortly after, having chosen to engage rather than run or hold. However, the champion made it to the end of the round.
Having taken Lee to the brink, Saunders took his foot off the pedal in the fourth and fifth, allowing Lee, who landed with one punishing left, back into the fight.
However, as the fight reached the midway point the suspicion was that Lee was not making Saunders work hard enough, Saunders having tired down the stretch despite beating Chris Eubank Jr in 2014.
As the rounds ticked by, Lee's left hand was always cocked but rarely thrown and there were boos and jeers at the end of the ninth round. But credit for Lee's reluctance to engage should be given to Saunders, who displayed excellent movement and so was rarely in range.
Lee did land with a thunderous left towards the end of the 11th, but Saunders took it well. And an anticipated onslaught from the champion in the final round never materialised.
Saunders, a former British, European and Commonwealth champion, is unbeaten in 23 pro fights and could now face a rematch with Eubank Jr.
Eubank Jr lost a narrow decision against Saunders last November but looked much-improved in stopping Ireland's Gary O'Sullivan last week.
Smith became the first of Liverpool's four fighting Smith brothers to win a world title when he stopped American John Thompson in October.
And the 27-year-old had far too much class for his Manchester rival Kelly, breaking him down with his superior power and accuracy, his left hook particularly potent.
By the fourth round much of the snap had been punched out of Kelly and in the sixth the desperate challenger was deducted two points for a blatant headbutt.
And in the following round, referee Marcus McDonnell stepped in after another Smith assault, as Kelly's trainer Ensley Bingham waved the white towel.
Kelly, 23, was taking part in only his 17th professional fight. Of his 16 previous opponents, only five had winning records.
Smith, who is now unbeaten in 23 pro fights, has options to unify the 154lb division. Cuba's Erislandy Lara is the WBA champion and American Jermall Charlo the IBF champion.
On the undercard, Cheshire's Paul Butler continued his quest for a second world title with a sixth-round stoppage of Romania's Silvio Olteanu.
Twenty seven-year-old Butler, a former bantamweight world champion, was beaten when challenging for Zolani Tete's IBF super-flyweight title in March.