Kell Brook's promoter Barry Hearn says Amir Khan has being avoiding his client by chasing unrealistic fights with Floyd Mayweather and Manny Pacquiao.
Khan has been unable to secure a major opponent in the United States, with Mayweather instead opting to end his glittering career against Andre Berto and Pacquiao set to face Timothy Bradley in April.
Hearn says Khan's pursuits of such big names were futile and have been used s an excuse to sidestep IBF welterweight champion Brook.
"I'm very disappointed because Khan has been almost impossible. He doesn't seem to want to fight anybody. [Being in America] is an excuse," he told Sky Sports.
"I can make excuses too - I want to fight Deontay Wilder myself, right now. Am I going to get that fight? Extremely unlikely.
"What I'm saying is that you have to be realistic and live in the real world. He spent 18 months chasing Floyd Mayweather without one per cent chance of ever fighting Floyd Mayweather. Then he spent six months chasing Manny Pacquiao."
However, Hearn believes a fight between Khan, who has not been involved in a world title fight in over three years, and Brook is edging closer as the 29-year-old runs out of potential opponents.
"I'm getting more optimistic because, one by one, all of Khan's alternatives [are disappearing]," Hearn said.
"He doesn't want to fight Brook. He was gambling that he'd get a bigger payday, but he'll get a lot of money for fighting Brook - but he may get beaten and I think he probably will."