Keith Thurman
On 2 September 2015, Hearn announced a deal had been reached for Brook to defend his title against Argentine slugger Diego Chaves (23–2–1, 19 KOs), after a deal could not be made with Brandon Rios. The fight was scheduled to take place at the Motorpoint Arena in Sheffield on 24 October, which would be Brook's third fight in seven months. Brook praised Chavez ahead of the fight, "Chaves is a rough, tough, durable fighter who is very dangerous. He's bringing something new to the table. He's coming off a draw to Tim Bradley, was ahead on the cards against Brandon Rios until he was disqualified and gave Keith Thurman a solid fight, so we know what level he has mixed at and how good he is." The fight was postponed and ultimately cancelled on 16 October after Brook injured his ribs during a sparring session. The rest of the card still took place as scheduled.