Former world heavyweight champion Vitali Klitschko has claimed that Anthony Joshua cannot defeat the best Wladimir Klitschko.

Joshua and the younger of the Klitschko siblings are scheduled to go head to head at Wembley Stadium on Saturday night, with Joshua's IBF belt and the vacant WBA title on the line.

Joshua is regarded as the marginal favourite by the bookmakers, but Vitali has insisted that his brother is near unbeatable if he is 100% focused on the bout.

The 45-year-old told BBC Radio 5 live: "Nobody is perfect. Everyone has strong sides and weak sides. Wladimir's weak side is his concentration.

"That cost him the title against Fury. I've never seen him focused like this. If he is concentrating 100%, Joshua does not have a chance. Wladimir understands this is the fight of his life."

Vitali is considered to be one of the greatest heavyweights of all time, with his only two defeats in 47 bouts as a professional coming due to injury.