Wladimir and Haye had been due to meet earlier in the year
Former undisputed heavyweight world champion Lennox Lewis believes new WBA holder David Haye can defeat IBF and WBO king Wladimir Klitschko.
But Lewis feels the Ukrainian's brother Vitali, the WBC champion, would be an altogether different proposition.
"Of the two, I would say Wladimir is the easier," Lewis told BBC Sport.
Haye, 29, became Britain's first heavyweight champion since Lewis retired in 2003 by beating Russian Nikolay Valuev in Nuremberg, Germany.
Lewis's last fight came against Vitali in 2003 with the British boxer stopping the 38-year-old in the sixth round after a cut forced an end to the bout. It was one of the toughest fights of his career.
"Vitali is very tall, lanky and awkward and it took me a few rounds before I could get to him," Lewis added on BBC Radio 5 live's Sportsweek programme.
"He knows how to use his reach but one thing David has over all of us is speed and foot speed.
"If he can improve on that then he can really get in and do the same thing he did against Valuev which is hit without being hit. Like I said I see him beating one, but if he fights Vitali it will be very difficult for him."
Haye earned a majority points decision victory over 36-year-old Valuev on 7 November after a fine performance against the Russian champion.
It was a victory that impressed Lewis, especially considering the fact Valuev was seven stone heavier and nine inches taller than Haye.
"He was boxing a guy that was way bigger then him in height and weight and who is really a freak of nature," said Lewis.
"But David showed what a smart boxer he is by taking those disadvantages and turning them into advantages by using his speed and punching ability and movement to stay out of harms way.
"This is the art of boxing, the sweet science of hitting without being hit and he displayed that wonderfully and came home with the belt."
Haye had been due to meet Vitali Klitschko on 20 June in London earlier this year but instead made a mandatory defence against Juan Carlos Gomez.
He will make enormous amounts of money now. The fact he has a belt now means that when he goes to negotiate his next title the terms will be more even
And following that cancellation Haye turned his attention to 33-year-old Wladimir, but their fight at Schalke 04's Veltins Arena was called off after the Brit suffered a back injury in training.
It looked like that fight would be re-scheduled but Haye was reportedly unhappy with the terms he was being offered and opted to meet Valuev instead.
The Londoner is set to face mandatory challenger John Ruiz next and Lewis believes that if he gets through that fight, the earning potential for Haye is massive.
The former cruiserweight king will also be able to negotiate on a level playing field, avoiding the problems he had with the Klitschkos, and will also have a say on where his fights are likely to happen.
"He will make enormous amounts of money now," added Lewis.
"The fact he has a belt now means that when he goes to negotiate his next title the terms will be more even.
"I'm very happy for him and for Britain."