The only man to fight Canelo Alvarez and Terence Crawford has predicted that size will not matter in Las Vegas on Sept. 13.

Alvarez, the undisputed super middleweight champion, will put his titles on the line against Crawford at Allegiant Stadium live on Netflix next month.

The Ring's No.3-rated pound-for-pound fighter Crawford, a former undisputed lightweight champion, has most recently campaigned in the 154-pound division but will jump up 14lbs and two weight classes to challenge Alvarez for his titles.

Khan, 38, is their only common opponent. The former unified junior welterweight champion from England was knocked out in the sixth round by Alvarez across in 2016 in Las Vegas. Three years later, Crawford stopped Khan in the very same round during their welterweight title fight in New York.

So the Bolton man, an Olympic silver medalist, can make his pick from the unique position of having fought both men. And he believes slight underdog Crawford will upset the oddsmakers by securing a famous victory.

"I'm the only guy to share the ring with both guys, and I've always said they're both great at what they do," Khan told Sky Sports. "When I fought Canelo, he was easier to hit. He had slow feet but fast hands, which I never expected. But he did have a lot of power, so that is what Crawford needs to be wary of.

"But then again, I saw a picture of Crawford where he was weighing around 180lbs. He looked strong and big. It looks like he holds the weight well.

"I do lean more towards Crawford in this fight, because he's the fresher fighter."

The 35-year-old Alvarez (63-2-2, 39 KOs) has been a pro since he was 20 years old. He has also had bruising encounters with Gennady Golovkin while also suffering defeats against Floyd Mayweather and Dmitry Bivol.

Crawford is older at 37 but has had 26 fewer professional fights, has never been beaten and, in Khan's opinion, has fewer miles on the clock.

"He's not been in too many wars like Canelo has been in," he said. "This is top-level boxing, and I don't know who is going to win but I do lean more towards Crawford."