Deontay Wilder retained his WBC world heavyweight title with a fifth-round stoppage of Gerald Washington.
Wilder, 31, participating in his first fight since breaking his right hand in his July victory over Chris Arreola, showed some rustiness on Saturday in his hometown of Birmingham, Alabama.
But he sprang to life in the fifth, flooring fellow American Washington with a right-left combination.
"I'm still here," said Wilder. "We're going to keep the fights coming."
Wilder, who won the title in 2015 with a unanimous 12-round decision over Canadian Bermane Stiverne, now has a 38-0 win record, 37 of which have come by knockout.
For Washington, it was a first defeat in 19 bouts.
The 34-year-old had stepped in to the fight after Wilder's planned opponent, Poland's Andrzej Wawrzyk, tested positive for a banned substance,
Wilder's latest victory sets up the prospect of future unification fights.
Britain's unbeaten Anthony Joshua and Ukraine's Wladimir Klitschko meet on 29 April in London for the WBA and IBF titles, while unbeaten WBO champion Joseph Parker of New Zealand is set to face another Briton, Hughie Fury, on 1 April in Auckland.
"I am ready for Joseph Parker. Are they ready for me?" Wilder added.