Andy Lee seized the WBO middleweight title with a dramatic stoppage win over Matt Korobov in Las Vegas.
Korobov appeared to edge the early rounds with his superior work-rate, but was badly hurt by a determined assault from Lee, who can now look ahead to a fight with Billy Joe Saunders, his mandatory challenger.
In a battle of two southpaws, the Russian seemed to land the crisper punches as Lee took time to find his range.
But the 30-year-old suddenly uncorked a huge hook in the sixth that left Korobov on unsteady legs. Sensing that victory was in his grasp, Lee unloaded 17 unanswered punches and Bayless stepped in to prevent further punishment.
An emotional Lee dedicated the win to his former trainer Emanuel Steward, who passed away in 2012, and current cornerman Adam Booth.
"This title is for him (Adam Booth) but it is also for the man that made me, Emanuel Steward," he said. "I lived with him for seven or eight years and I learned so much from him I owe this to him.
"He said I would win the world title and tonight I made the dream come true.”
On the same bill, welterweight Timothy Bradley was held to a split draw by Diego Chaves, despite appearing to outwork the Argentine.
Bradley was returning after a rematch points defeat by Manny Pacquiao, but endured more frustration as one judge scored it 119-109 for him, with another carding a 114-114 tally, while a third gave it 116-112 to Chav es.