Amir Khan's first world title tilt has been thrown into doubt after his opponent Andreas Kotelnik threatened to postpone because of a tooth infection.
The 22-year-old is due to meet Ukrainian WBA light-welterweight champion Kotelnik in London at the 02 Arena on 27 June.
But Kotelnik may have to delay or pull out of the fight altogether.
A spokesman for Khan's promoter, Frank Warren, said: "We're waiting to find out whether the fight will be delayed."
Khan defeated Mexican legend Marco Antonio Barrera in a thrilling lightweight contest in Manchester in March, but he is set to move up a division to take on Kotelnik for his first attempt at world title glory.
But if the champion is unable to make the fight, promoter Frank Warren will either postpone it for several weeks or secure an alternative opponent.
"We're looking at a couple of things but if we can still go ahead on the 27th with another opponent we will," added Warren's spokesman.
"Frank is working on it and we should know something on Monday or Tuesday."
The card also features British middleweight champion Matthew Macklin defending his title, Matthew Hall and Anthony Small meeting for the British and Commonwealth light-middleweight belts.
It will also include the third professional appearances of former amateur stars James DeGale, Frankie Gavin and Billy Joe Saunders.