James DeGale hailed the fulfilment of a dream after becoming the first British boxer to win both an Olympic gold and a professional world title.
DeGale, 29, beat the United States' Andre Dirrell on points in Boston on Saturday night to claim the vacant IBF super-middleweight belt.
The Londoner said on Twitter on Sunday: "Please tell me it wasn't a dream!? I don't have to dream any more..I did it! Can't thank you enough for your support #andthenew #history ".
Afterwards, DeGale dedicated the victory to the late Irish boxer Darren Sutherland who tragically took his own life nearly six years ago.
"It's for Darren Sutherland aswell, of course. My late rival. When he took his life back in 2009 it was horrendous. From when he passed, I've always had 'DS' on my shorts. And this world title is for him aswell. Please believe me.
"A great guy. A great fighter. Unbelievable fighter. We've had some great, great scraps. It's for him."
DeGale, who won a middleweight gold medal at the Beijing Olympics in 2008 beating Sutherland in the semi-final, won a unanimous points decision against his 31-year-old opponent. He becomes the first fighter to achieve both an Olympic gold for Britain and a world title - Lennox Lewis' Olympic gold came for Canada.
DeGale said on Sky Sports after the fight: "I've finally done it. It's an unbelievable feeling, I'm world champ. I made history. I will take on any super-middleweight in the world. I'm hard to beat when I'm at my best."
DeGale floored Dirrell in the second round with a left to the chin but the 31-year-old beat the count, but he recovered to pose some challenge to his opponent in the later rounds.
A flurry from DeGale in the final round made sure that the victory was his however. American judge Daniel Fitzgerald and British judge Howard Foster both scored the fight 114-112, while Canadian Alan Davis scored it 117-109.