Amir Khan's trainer Virgil Hunter believes his fighter is now back on the path to world title glory.

Khan split from previous coach Freddie Roach and turned to Hunter last year after his career stalled with back-to-back defeats against Lamont Peterson and Danny Garcia in world title fights.

Khan began what he hopes is a march back to the top with victory over Carlos Molina last December and he aims to progress further by seeing off Mexican Julio Diaz in Sheffield this weekend.

Hunter is confident the 25-year-old former world lightweight champion will regain his lost status.

Yet while he expects Khan to learn from the mistakes he made, he believes other errors were made by the previous regime that surrounded the Bolton fighter.

Hunter said: "When he came to us we had concerns about his past fights.

"We had him properly assessed so we could begin the necessary process to correct the problems.

"All you ask for is to learn from mistakes, and he will, but there were mistakes made against him too.

"He has gone into fights outweighed by 12 or 13 pounds and this is something that shouldn't have happened.

"If he is the king of the hill, he dictates the terms.

"But there is no doubt at all he can be world champion again.

"He is in great physical shape, he is still young, he has strength of character.

"He is the only fighter I have known personally - and I've known some - in the world of boxing who hasn't been affected by a knockout.

"His troubles have been connected to mistakes and not that the other guy was better than him.

"Because of that, he is still intact confidence-wise."

Khan takes on Diaz in a non-title bout set at a "catch weight" of 143 pounds, a mark between super lightweight and welterweight.

It will be the heaviest Khan has fought at while California-based Diaz, himself a former world lightweight champion, is coming down slightly after recent welterweight fights.

Khan claims to have been reinvigorated under Hunter and admits weight had been a problem area in the past.

He said: "Vergil has had a huge impact on my boxing, on my style, making sure everything sticks.

"He is like a teacher, making sure I do things right, making me understand the sport of boxing.

"It's not just fighting, you're a boxer and have to think about every shot you throw, every move you make.

"It is totally different now, the way I approach a fight and make the weight for a fight.

"I am healthy and ready instead of being so dry. I know what mistakes I made before and I am not going to make them again."

Diaz also feels the fight can propel him back into the world title frame.

The 33-year-old, who has lost seven of his 48 fights but won 29 out of 40 by knockout, is convinced he still has a lot to offer.

Diaz said: "I know I have a big fight in front of me, against a tough warrior.

"He has fought fighters when he has been out on his feet but he has finished them. Not a lot of fighters can do that. He has the heart of a lion.

"But I am ready for that. I came to fight and I have trained hard.

"Amir Khan is my ticket and I am going to get it."

The fight headlines a packed card that also sees Khan's 21-year-old brother Haroon, after 66 wins as an amateur, make his professional debut in a four-round super flyweight contest against Bulgaria's Stefan Slavchev.

Haroon, who represented Pakistan at the 2010 Commonwealth Games, has taken some advice from his brother: "He said don't go out and try to please the crowd, that is when you make mistakes.

"If you go out there looking for a knockout, you can get knocked out.

"I am going to go out their try my best. I am going to keep my hands in but if a knockout chance comes, it comes."

Amir has spoken often of his brother's potential, and his desire to advise him, but when it comes to who is the best pound-for-pound fighter in the family, there is no doubt.

Amir said: "I think it is probably my mum! She tells us both off, and she tells it how it is.

"It'll be a nervy night for mum. She won't be coming to the fight but she'll be at the hotel and we'll see her straight afterwards."