Bolton's Amir Khan prepares to take on Mexico's Julio Diaz

Bolton's Amir Khan has warned Julio Diaz he has a surprise in store for him in Sheffield this weekend.

Khan takes on the Mexican, like himself a former world champion, in a bout he hopes will propel him back into title contention at the Metropoint Arena tomorrow.

The Bolton fighter's career stalled after he controversially lost his WBA and IBF light welterweight belts to Lamont Peterson in December 2011 and then failed to take the WBC equivalent off Danny Garcia last year.

He brought in a new trainer in American Vergil Hunter and began his road to recovery by seeing off Carlos Molina last December.

Diaz, who is making his own bid to return to the top, was lined up as his next opponent in a 143-pound "catch weight" bout - a mark between super lightweight and welterweight - and Khan feels a new man ahead of the challenge.

Diaz claims to be aware of the Briton's weaknesses, but Khan said: "Julio is working on the old Amir Khan, that is what he is doing.

"There is a new Amir Khan now and he has not seen him yet. If he wants to work with the old Amir Khan he can do, but he'll be in for a shock on Saturday."

Khan also promised fans they will see a different fighter in what will be his first appearance in the UK for two years.

The 25-year-old said: "The last time they saw me here was against Paul McCloskey and I am a totally different fighter now.

"I won't let my fans down. Hopefully on Saturday we will be back to winning ways and it will take us to bigger fights."

Diaz, 33, is a former world lightweight champion but has been reinventing himself at welterweight and is not fazed.

He said: "Everybody was counting me out, saying I was done. With all those critics saying I don't have it any more - I am here.

"I am back, I am a refreshed fighter and people are going to see that."

The fight is the highlight of a packed card which also sees the professional debuts of Khan's younger brother Haroon and Olympic bronze medallist Anthony Ogogo.

Heavyweight Audley Harrison, 41, is also in action, taking on unbeaten American Deontay Wilder believing he still he has what it takes to become a world champion.

Harrison was widely written off after suffering his sixth professional defeat to David Price last year but he remains un deterred.

He said: "Some of you will say, 'He is crazy, he is delusional' but there is no doubt in my mind. Losing is all part of the journey.