The Bolton-born fighter won an online fan poll in May to become the undefeated boxer's next opponent, but the American instead opted to take on Marcos Maidana.
However, Khan believes that Mayweather will have a close eye on his bout against the Puerto Rican, who has clinched 35 wins from 39 fights.
"The fight's going to happen one day in the future, for sure," Khan told Sky Sports News. "I spoke to Floyd on the phone and he said, 'look champ, the fight will happen one day.'
"Mayweather will have his fans, his people watching the fight very closely, and if I put on a great fight, I know that it will probably give me the gateway to the Mayweather fight."
Khan's bout against Collazo will be his first fight in 13 months.