Amir Khan will face Australia’s Billy Dib next month after his original opponent, India’s Neeraj Goyat, was injured in a car crash.
Britain’s Khan, 32, was due to face Goyat in Saudi Arabia on 12 July and earn a reported £7m.
Former world featherweight champion Dib, 33, will replace Goyat and said the chance was his “real-life Rocky moment”.
“I hope Neeraj recovers quick and gets fully fit again,” Khan said.
Khan had spoken of his excitement at fighting in Saudi Arabia and said the bout was ideal for him because it offered a quick route back into the ring following his controversial defeat by American WBO welterweight champion Terence Crawford on 20 April, when he was accused of ‘quitting’.
In a video released on social media on Wednesday, Khan said: “Billy is a two-time world boxing champion and will be coming up [in weight] to fight me, just like I did with Canelo [Saul ‘Canelo’ Alvarez].”
The fight will take place at the King Abdullah Sports City in Jeddah.
Dib, who retired from boxing after being beaten by American Tevin Farmer in August 2018, announced he was returning to the ring eight months later.
After claiming a first-round knockout on the undercard of an IBA world featherweight title fight in Australia in April, Dib will head to the Middle East to face Khan in just over two weeks’ time.
“In life you get a limited number of opportunities to do something monumental, and like the greatest in any industry will tell you, when an opportunity comes knocking you answer,” he said.
“This is my real-life Rocky moment.”