Chris Eubank Jr will now fight Anatoli Muratov on Saturday, live on Sky Sports, after Sven Elbir tested positive for coronavirus.
Britain's middleweight contender returns at The SSE Arena, Wembley on Saturday and victory would keep Eubank Jr on course for a WBA title shot this year.
His new opponent, Muratov, is ranked No 7 by the WBA after winning 24 of his 27 bouts, racking up 17 knockouts in that time and losing only twice.
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Eubank Jr says he is more fired up than ever to fulfil his world title ambitions after seeing his friend Anthony Joshua lose his belts in Saturday's unanimous points defeat to Oleksandr Usyk.
"Absolutely, I'm fired up," said Eubank Jr, who joined the Sky Sports team at Tottenham Hotspur Stadium.
"Obviously Anthony Joshua is a friend of mine. I'm a little deflated that he lost, but it's part of the game. We've all been there.
"If anything, this makes me want to fight even harder. I know the feelings he's going through now.
"The first thing you want to do is get back in the ring and win. We're going to put on a hell of a show."
Eubank Jr produced a dominant points win over Marcus Morrison, in his first fight with new trainer Roy Jones Jr in May.
The 32-year-old says he resisted the desire to seek an early stoppage, but plans to unleash his ruthless instincts this weekend.
"I can be whatever I want to be," Eubank Jr told Sky Sports. "It all depends on what I'm trying to achieve on the given night.
"On that given night, I wanted to achieve 10 rounds. I wanted to experience what it was like to have Roy Jones in my corner, and to listen to his instructions, and to shake off some of that ring rust.
"I had been out of the ring for a long, long time.
"Could I have stopped the fight earlier? Yes, but that wasn't my goal.
"That's not how it's always going to be. Fighters need to understand that was a freak occurrence. Most of the time, if I see an opportunity, I'm going to take it. You're going to go.
"On that occasion, it wasn't the case, but in my next performance I will be looking for the stoppage early."
Chris Eubank Jr returns on Saturday night, live on Sky Sports.