Audley Harrison will return to action on the undercard of Joe Calzaghe's super-fight with Bernard Hopkins in Las Vegas on Saturday night.

And the former Olympic gold medallist, who was knocked out by Michael Sprott in his last fight, still believes he has what it takes to reach the top.

"It's not the end, it's the beginning," said Harrison. "My whole life has been about adversity, my whole boxing career has been about proving people wrong."

His comeback from being knocked out by Sprott 14 months ago have been derailed by a car crash and the death of his brother.

Harrison faces little-known Floridian Jason Barnett, who has a record of 10 wins and six defeats, in an eight-round contest.

And the Londoner, who now lives in Vegas, believes victory will eventually lead to a world heavyweight title.

"I don't need to box," the 36-year-old continued. "But I've got a goal that I have set myself and I'm not going to accept it when I get knocked down.

"When things don't go your way, it's the measure of the man how you come back."

Harrison turned professional amid great fanfare in 2000 after striking gold at the Sydney Olympics, but his career soon went off track.

Deciding to manage his own career, Harrison picked poor opponents and made brash pronouncements and soon lost the support of the British public.

After 19 straight victories, Harrison was first defeated by fellow Brit Danny Williams, then American Dominick Guinn, before being flattened by Reading's Sprott last February and booed out of the ring.

His match with Barnett will be the first in a new deal with promoter Frank Warren, previously one of his staunchest critics.

"Everybody deserves a second chance," said Warren.

"He's got his opportunity and now he has to go and prove himself because the public won't buy into it if he doesn't produce the goods.

"How long this deal lasts will be based on how successful Audley is, but he needs to have three fights relatively quickly, and get himself back out there and winning again, and then we'll see where we go from there."

Harrison's return makes a match with compatriot David Haye, who is stepping up to the heavyweight ranks after his devastating defeat of Enzo Maccarinelli in March, a possibility.

"I've spoken to David about it, and I've said that it's a fight for Wembley Stadium when either one of us has won a world title," said Harrison.