Amir Khan rejected the opportunity to fight Manny Pacquiao earlier this year, according to the Filipino fighter's promoter, Bob Arum.
Khan, 28, takes on Devon Alexander in Las Vegas on Saturday 13 December in a contest he hopes will catapult him further into contention for bouts with the welterweight's elite.
But, according to Arum, Khan's camp was not interested in arranging a meeting with Pacquiao when it was proposed following the 35-year-old boxer's rematch victory over Timothy Bradley in April.
"After Pacquiao's second fight with Timothy Bradley, I tried to see if Khan was interested in fighting Manny and if it was legally possible," Arum told the Daily Telegraph.
"The first guy I asked was Nick Khan, who is the agent of Freddie Roach and a friend of mine.
"He came back and say they [Khan's advisers] gave him the runaround. We were told: 'No way.' They have contractual commitments to others which would prevent that fight from happening. So I dropped it."
Khan successfully fought Luis Collazo on the undercard of Floyd Mayweather's win over Marcos Maidana in May, hoping that victory would earn him a showdown with the five-weight world champion later in the year.
But Mayweather, 37, opted for a rematch with the Argentine, with Khan's Ramadan commitments throughout July at odds with strength and conditioning preparation needed for that September slot.
Khan returns to the ring against Alexander in a fight initially scheduled to take place this time last year, only for it to be shelved as his camp pursued a meeting with Mayweather in May 2015, before eventually fighting Collazo on the undercard.
Having dominated Collazo in his latest outing, Khan is hoping another stellar performance will act as an audition for his dream fight with the unbeaten welterweight.
"This is definitely an audition, or a dress rehearsal for a fight with Mayweather," Khan said. "It will be the opportunity to imagine what it will be like when I'm fighting against Floyd Mayweather, the biggest fight of my career."