Former world champion Amir Khan (31-4, 19 KOs) had suspicions in his last fight, when he moved up to a catch-weight of 155-pounds to challenge then middleweight champion Saul "Canelo" Alvarez in May of 2016 at the T-Mobile Arena in Las Vegas.

Khan started well in the early rounds, but all it took was one-punch to knock him out cold in the sixth round.

The Bolton boxer has long claimed that Canelo gained a tremendous amount of weight when they stepped in the ring - and he believes the Mexican superstar was close to 180-pounds or more.

Canelo has been under the gun in the last few weeks, after Golden Boy Promotions revealed last month that their boxer had tested positive for the banned substance clenbuterol.

He was placed under a temporary suspension by the Nevada State Athletic Commission and ordered to appear at a disciplinary hearing on April 18th in Las Vegas.

Based on the likelihood of getting hit with a full suspension for at least six months, Canelo withdrew from a scheduled rematch with IBF, IBO, WBA, WBC middleweight champion Gennady Golovkin, which was scheduled for May 5th. 

Khan, who returns to the ring on April 21 against Phil Lo Greco in Liverpool, admits that he sensed something was odd about the high amount of post-weigh-in mass that Canelo had gained by the time they entered the ring.

“I’m not saying he was on something when I fought him, but you could see he’d put on a lot of weight," Khan said to The Telegraph.

“I hope he was clean when I fought him, he’s always going to say he was clean. Only God knows. But he got so big, so quick after the weigh-in. He put on over 35 pounds of weight. I thought there must be something wrong there. I could see how strong he was when I fought him."

Khan is also very firm in his belief that Canelo must be punished to set an example for everyone else in the sport.

“He’s been caught taking drugs which is illegal. He's a big name in the sport, and I think that he definitely needs to be taught a lesson," Khan added.

"Otherwise all fighters will think it’s okay. There’s a saying: once a cheat, always a cheat. I’ve never taken drugs in my life and never will, I want to win fights on my own skills and my own abilities. But when people need that bit of advantage, it’s unfair.”