THE worldโ€™s leading trainer believes Amir Khan can succeed in upsetting Terence Crawford โ€”ย even though he considers the American the finest fighter in the world.

Khan challenges the great WBO welterweight champion at New Yorkโ€™s Madison Square Garden on Saturday in what could prove to be his defining fight.

Trainer Freddie Roach is as familiar with Khan, having once trained him at his famous Wild Card gym, as he is with the level Crawford is competing at after inspiring the great Manny Pacquiao to his peak years.

Fights with Pacquiao and Floyd Mayweather previously eluded Khan when he hoped to challenge one of the worldโ€™s two leading fighters, but this weekend the opportunity the 32-year-old from Bolton has desperately wanted finally arrives.

โ€œKhan can pull off the upset if he fights the right fight,โ€ Roach told Press Association Sport.

โ€œI always said, if Khan goes out there and boxes and wins one round at a time, and keeps doing it, and not look for the knock-out [he can win].

โ€œWhen he hurts him, donโ€™t open up on him because thatโ€™s when he gets caught, and puts himself in harmโ€™s way.

โ€œHeโ€™s a very good boxer; he still has a lot left in him. His speed; his foot-speed and hand-speed are unbelievable. I remember him and Pacquiao sparring competitively, it was about even. Heโ€™s definitely at that high level; hopefully Father Time hasnโ€™t got to him yet.

โ€œI still think heโ€™s young enough and fresh enough to have moments of success, but I like Crawford to win the fight.

โ€œHeโ€™s a big underdog; Crawfordโ€™s the best fighter in the world. Pretty soon him and [fellow welterweight] Errol Spence are going to have to fight each other.โ€

The decorated Roach is reminded of Mayweather-Pacquiao by the rivalry between Vasyl Lomachenko and Crawford, and also believes that Khanโ€™s task has been made even more difficult because Crawford will want to respond to Lomachenkoโ€™s destruction of Anthony Crolla last weekend.

โ€œHe does have to produce a good performance,โ€ he said. โ€œIโ€™ve seen him go out and box before, heโ€™s a very good boxer, but Iโ€™ve seen him blow guys away also.

โ€œHe can start very quickly and knock out guys in only two rounds. He can punch, too, heโ€™s not just a good boxer but a good puncher also. Heโ€™s more of a complete fighter than Lomachenko, and for what happened last week heโ€™s going to have to jump on Amir right away.

โ€œYou have to control your fighter and get him ready for what heโ€™s getting ready for, and make sure he stays on that [instead of being concerned with a rivalry]. It pretty much affects everyone in camp.โ€

Amir Khan fights Terence Crawford live on BT Sport Box Office, Saturday April 20. For more informationย www.bt.com/btsportboxoffice