Lewis retired eight months after beating Vitali Klitschko

Lewis, who quit following a hard-fought win over Ukrainian Klitschko in 2003, told BBC Radio Five Live that Williams would be the big underdog in Las Vegas.

"Just looking at the fight and the statistics, I realise that Klitschko has a big advantage," he said.

"Danny is going into the fight with a lot of things against him."

Whatever they offer me to fight won't be enough Lennox Lewis

Lewis says Williams will find it difficult to get at Klitschko because he is much smaller and has a shorter reach than the champion.

But the 39-year-old Brit is not totally dismissive of Williams' chances.

"What he needs to do if he really wants it, is go after Klitschko, to get inside and hit him to the body," said Lewis.

"Then, if he can hit him on the face and open up a cut, perhaps he can win the fight that way."

Meanwhile, Lewis has reiterated his desire to remain retired, saying no amount of money could sway him.

Lewis takes controversial win

Klitschko, who was angry with the manner of his loss to Lewis in 2003, has repeatedly tried to coax his rival back into the ring.

"I would love to fight Lewis again and I think a lot of people want to see it," said the 33-year-old, who was controversially stopped by a cut to his eye when leading on all judges' cards.

But Lewis plans to keep his distance, although he will be ringside at the Mandalay Bay Casino to watch Klitschko take on Williams.

"At some point in your life, you have to think about your health and future, so whatever they offer me to fight won't be enough," said Lewis.