Amir Khan has promised to beat Danny Garcia after his next opponent's father claimed the former world champion was over-rated ahead of their July 14 meeting.

Garcia stepped in to face Khan, pictured, at the Mandalay Bay in Las Vegas after the latter's rematch with Lamont Peterson fell through when the American tested positive for testosterone.

Peterson had become World Boxing Association and International Boxing Federation light-welterweight champion when he beat Khan by a split decision in Washington in December.

Garcia's father Angel told a press conference in Los Angeles: "Khan is an over-rated fighter. Peterson whupped him like an octopus and then he blamed it on the judges."

Garcia took the World Boxing Council light-welterweight title from Erik Morales and has now put the belt on the line against Khan, with both fighters managed by Golden Boy Promotions.

Following the taunts by Garcia's father, Khan said: "Danny's father does a lot of talking, but he's not the one who's going to be in the ring. When I beat your son am I still going to be over-rated? We will see."

Khan has something to prove following the defeat to Peterson but does not underestimate the challenge he faces against Garcia.

He said: "I know how good Danny is. He's had a good win against Erik Morales. This is going to be a big test for me."