Lennox Lewis has urged Daniel Dubois to prove he is a world champion in the ring when he puts his IBF belt on the line against Anthony Joshua on Saturday.

Dubois and Joshua clash in the first great all-British heavyweight world title showdown since Lewis and Frank Bruno gripped the nation with their Cardiff Arms Park collision in 1993.

Lewis entered the ‘Battle of Britain’ having proved his elevation to WBC champion without throwing a punch was justified by outpointing Tony Tucker five months earlier.

WBC king Riddick Bowe had refused to fight him and famously dumped the belt in a rubbish bin.

Lewis sees Dubois being driven by the same motivation after the heavy underdog was given the IBF title in June following Oleksandr Usyk’s decision to vacate in order to pursue a rematch with Tyson Fury.

“I didn’t feel like a world champion because I wanted to prove it in the ring,” said Lewis, who will be working on the TNT Sports Box Office live coverage of the Wembley showdown.

“I didn’t want that opportunity for people to say ‘ah yeah, well he didn’t win it, they gave it to him’. Who wants to win a title that they give to you?

“I’m glad that they awarded it to me – awards sounds better – but as far as taking it into the ring, you’ve got to prove it.

“Daniel’s got a belt and he’s got to go in there and defend it. It’s hard to get a belt, but it’s even harder to keep it.

“He’s in that position now where people may look at him as an underdog. He has that position where he can say ‘no, you’re wrong, I’m a champion, I can beat the champion and this is my time’.”

“I think he has a great chance against Joshua. These opportunities only come once in a lifetime so you have got to seize the moment.”

Joshua’s greater experience, especially in stadium fights, is expected to see him crowned world heavyweight champion for the third time in front of a British record 96,000 crowd.

Dubois is a dangerous opponent, however, having knocked out 20 of his 21 victims.

Lewis, the division’s last undisputed heavyweight champion until Usyk beat Fury in May, believes his seventh-round stoppage of Bruno when he was 28 offers an important lesson on how Dubois should manage the occasion

“Me and Frank Bruno were trying to knock each other out. It was more than just trying to show each other our skills. We were trying to show skill, but with a stamp on it,” Lewis said.

“He started off really fast, I started off fast. I think he could see every punch I was throwing.

“And then I calmed down and caught him with a good punch. I had to slow my mind down because I was starting to rush. For Daniel, he has to go out there and not be over-hyped, or over-exerted.

“Both guys are going to be wary of each other’s power because they both have that knockout power. It’s going to be an interesting fight. It’s about whoever can last.”

Watch Riyadh Season Card: Joshua v Dubois, live on TNT Sports Box Office from 4pm on Saturday 21 September. Find out more at tntsports.co.uk/boxoffice