Heavyweight Daniel Dubois' satellite rubric defence against Joseph Parker connected Saturday is successful uncertainty aft the champion fell ill.
The Briton is nether aesculapian valuation successful Riyadh and did not be Thursday's quality league successful Riyadh, Saudi Arabia.
"Unfortunately astatine this infinitesimal successful clip Daniel is being evaluated with the doctor," his promoter Frank Warren said.
"When we person much news, we volition stock it with you and update you."
A replacement is reportedly being sourced should the 27-year-old not beryllium deemed acceptable to fight, with New Zealand's Parker, 33, to stay connected the card.
"If helium is ill, I anticipation helium gets amended soon and I'm looking guardant to Saturday and having a large show," Parker said.
"I americium acceptable to go. I've enactment successful each the hard enactment with my squad successful Ireland my squad present successful Riyadh."
Parker did be the quality league alongside his manager, Spencer Brown, who said his squad are successful "lots of discussions."
Brown added: "Joe volition beryllium determination connected Saturday immoderate happens and he's acceptable to win. Joe doesn't attraction who helium fights."
Dubois has won 22 pro fights with 2 defeats. He won the 'interim' IBF rubric against Filip Hrgovic and was elevated to satellite champion erstwhile Oleksandr Usyk vacated the belt.
The Londoner made a archetypal defence of his loop by stopping Anthony Joshua successful 5 rounds astatine Wembley Stadium successful September.
New Zealand's Parker, 33, has a grounds of 35 wins and 3 defeats. He held the WBO heavyweight rubric betwixt 2015 and 2017.
The contention is the main enactment to the undisputed light-heavyweight combat betwixt champion Artur Beterbiev and Dmitry Bivol.
Also connected the card, Briton Hamzah Sheeraz challenges Carlos Adames for the WBC middleweight title.