Errol Spence Jr has been ruled out of his fight with Manny Pacquiao on August 21 due to an eye injury.
Welterweight Spence had been due to defend his IBF and WBC titles against the 42-year-old Pacquiao, who has not fought since beating Keith Thurman to become WBA champion in July 2019.
That victory made 'Pac-Man' the first four-time champion at the weight limit, though he was knocked down to champion in recess by the WBA due to inactivity.
While Pacquiao will not be fighting his planned opponent later this month, he will still be in action on the Las Vegas bill.
The Filipino will instead take on Yordenis Ugas, who had originally been scheduled to defend his WBA belt against Fabian Maidana as part of the undercard.
Spence marked his comeback following injuries sustained in a car crash with an impressive victory over Danny Garcia last year, but his career is once again on hold.
The 31-year-old - nicknamed 'The Truth' - has suffered a retinal tear in his left eye, forcing him to pull out of the much-anticipated showdown.
"Went to three different doctors all said the same thing I'll be back for the winner for sure," Spence tweeted.
He followed up with "I came back from worse" in a further post, appearing to reference the vehicle accident in October 2019 that left him in intensive care.
Spence made clear on Twitter he is already planning to take on the Pacquiao-Ugas winner once he is cleared to return to action.
"I pray for a full and complete recovery for Errol Spence Jr," Pacquiao tweeted following the change.
