Heavyweights Dillian Whyte and Kubrat Pulev have been ordered to fight by the International Boxing Federation, says the Briton's promoter Eddie Hearn.
The bout would be a final eliminator to become the mandatory challenger for the IBF world heavyweight title held by Whyte's compatriot Anthony Joshua.
It could complicate Joshua's hopes of a unification fight with Deontay Wilder.
Joshua, who is also the WBO and WBA champion, may have to face either Whyte or Pulev, or give up his IBF belt.
"Just received a letter from the IBF ordering a final eliminator for the mandatory position between Dillian Whyte and Kubrat Pulev," tweeted Hearn.
"Interesting times for the division."
Joshua wants Wilder's WBC belt after winning the WBO title with a unanimous points win over Joseph Parker on Saturday.
A bout between Joshua and American Wilder would deliver the first man to hold all four major heavyweight titles.
Luke Reddy, BBC Sport boxing reporter
The boxing world moves fast.
On Saturday, Whyte mouthed "easy money" after watching Alexander Povetkin beat David Price. He even got close to the ring to say he'd face the Russian.
Two days later, it's now Pulev - and a win would line up a second Whyte v Joshua fight since they turned pro.
This underlines just how hard it will be for Joshua to keep all his belts as the IBF, WBA and WBO can raise challengers in this way. It shows the limited time on offer to make Joshua-Wilder, with all four belts up for grabs.
Whyte will care little for such politics. He beat Joshua in the amateur game and wobbled him when they met in the paid ranks.
He will see this as a chance at the big time.