Amir Khan has promised to beat Danny Garcia after his next opponent's father claimed the former world champion was overrated ahead of their July 14 meeting.
Garcia stepped in to face Khan 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 WBA and IBF light welterweight champion when he beat Khan by a controversial split decision in his native Washington in December.
Garcia's father Angel told a press conference in Los Angeles: "Khan is an overrated fighter. Peterson whupped him like an octopus and then he blamed it on the judges."
Garcia took the WBC light welterweight title off 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 at the end of the day he's not the one who's going to be in the ring.
"When I beat your son am I still going to be overrated? We will see what happens."
Khan has something to prove following the defeat to Peterson but does not underestimate the challenge he faces against Garcia.
He said: "After the Peterson fight fell through we were quite desperate to get a fight because I was at my peak.
"Danny accepted the challenge. I know how good he is. He's had a good win against Erik Morales. This is going to be a big test for me."
Garcia said: "Khan's a great fighter, I'm a great fighter. When you put two great fighters together you get an awesome show. I'm ready to defend my title."