Julian Williams captured the WBA (Super) and IBF super-welterweight titles after a shock points win over previously undefeated champion Jarrett Hurd.
Williams (27-1-1) knocked down Hurd (23-1) in the second round on his way to a unanimous points decision at the EagleBank Arena in Fairfax, Virginia.
The judges scored it 116-111, 115-112 and 115-112 in favour of Williams, who is now undefeated in five fights since suffering a fifth-round knockout loss to Jermall Charlo for the IBF super-welterweight title in 2016.
"They told me I was done, that I had no chin," Williams said. "Jarrett's such a great fighter and he pushed me.
"I got so motivated because everybody was doubting me. I turned my Twitter off, I turned my Instagram off.
"I blocked out all the good stuff, I blocked out all the bad stuff. The boxing world, they make it seem like fighters take a loss and they can't come back, and I just knew that wasn't the case.
"Stop condemning fighters after they take a loss."
Hurd called for an immediate rematch after congratulating Williams in his post-fight interview.
"J Rock was the better man tonight," Hurd said. "He put me down for the first time in my career and he came out with a victory. No nerves had anything to do with it.
"There's definitely a rematch clause in our contract, and I'm going to go for it. I'm going to come back better than I was tonight."