Amir Khan has lamented Floyd Mayweather's latest snub after the pound-for-pound king opted to face Andre Berto in what could be his final bout on 12 September.
Khan believed he was on a collision course with Mayweather next month, despite an underwhelming points victory over Chris Algieri, a bout the Briton was expected to win comfortably.
Mayweather, though, announced on Tuesday evening he will face former welterweight world champion Berto, who shares the same trainer as Khan.
It is not the first time Mayweather has spurned Khan's advances and the Bolton fighter expressed his dismay at the setback.
"I'm disappointed not to have got the fight for what is the third time after having been one of the frontrunners," he said.
"However, there are many big fights out there for me and I'm going to continue working hard to establish myself at the top of the welterweight division."
Khan did concede that Mayweather, who improved his perfect professional record to 48-0 after beating Manny Pacquiao for the WBC, WBA and WBO welterweight titles in May, was entitled to fight whomever he wished.
"Floyd Mayweather has fought the biggest names throughout his career and has earned the right to face whoever he chooses," added Khan.
"I wish my stablemate Andre Berto and trainer Virgil Hunter the very best of luck in the fight.
"I have seen how hard Andre trains and works and know that he is ready to give Floyd a very tough night."
Mayweather has repeatedly insisted his final bout will be next month and he has chosen to face an opponent who has lost three of his last six fights.
Victor Ortiz ended Berto's unbeaten record as a professional four years ago, while the American also lost to Robert Guerrero and Jesus Soto Karass in 2012 and 2013 respectively.