Ukrainian heavyweight Oleksandr Usyk is waiting for Anthony Joshua's decision on a world title fight, according to his promoter.
Usyk, a former undisputed champion at cruiserweight, is the WBO's mandatory challenger for Joshua's strap.
The negotiations deadline of May 31 has elapsed, meaning it is now up to Joshua and his promoter Eddie Hearn to decide on their next move.
Speaking about a potential bout, Usyk's promoter Alexander Krassyuk said: "We are waiting for King AJ's decision whether he is brave enough to get dethroned."
When asked if he thought a deal would be struck, Krassyuk added: "I have no idea at the moment. We are expecting his decision."
The Watford-born fighter, who also holds the WBA and IBF belts, was ordered to fight Usyk following the breakdown of his undisputed clash with Tyson Fury.
The pair were close to agreeing a huge two-fight deal, but an arbitrator ruled in favour of Deontay Wilder and his contractual right to a trilogy bout against Fury.
The 'Gypsy King' will face Wilder on July 24 at the Allegiant Stadium, Nevada.
Boxing fans will be hoping to see a long-awaited undisputed fight after those events have concluded. It remains to be seen who will be there out of Usyk, Joshua, Fury and Wilder.
Despite his dominance at 200 lbs, Usyk doesn't seem to have the power to trouble heavyweight's big names. He defeated Dereck Chisora via unanimous decision last year but never looked like knocking the veteran out.
Joshua and Fury will be the favourites to retain their belts and set up an historic British clash. Fury has already won the WBC title from Wilder and will be confident about another dominant victory.