Anthony Joshua has labelled Lennox Lewis “a clown” and said they “are cut from a different cloth”.
Britain's Lewis remains the last undisputed heavyweight champion and enjoyed historic wins over Mike Tyson and Evander Holyfield, but has irked Joshua in the aftermath of his shock defeat against Andy Ruiz Jr.
"I can't look at that fight and agree that AJ was fully prepared," tweeted Lewis who also called into question the ability of Joshua's trainer, Rob McCracken.
Disappointed in AJ’s words but I understand that this “jealousy” narrative was only fabricated AFTER I criticized them for Wilder negotiations. All of the sudden im a hater. 🤷🏾♂️ Ask who benefits from such a simple minded narrative? Not AJ. Not me.— Lennox Lewis (@LennoxLewis) August 15, 2019
"Lennox is a clown. I don't respect Lennox," Joshua said on AJ: The Untold Truth.
It was suggested that Lewis left an impressive legacy but Joshua replied: "So? So am I.
"Me and Lennox are not the same. My legacy is to sit back and enjoy the younger generation coming up, and not to be involved. Just to appreciate what it takes to get there.
"Lennox isn't like that.
"Me and Lennox are cut from a different cloth."
Like Joshua against Ruiz Jr, Lewis also suffered shock defeats but he avenged both results by winning rematches with Oliver McCall and Hasim Rahman.
Joshua has his chance to do similarly against Ruiz Jr with the IBF, WBA and WBO heavyweight titles at stake on December 7 in Saudi Arabia, live on Sky Sports Box Office.
Joshua promised that would no longer concentrate on a future fight with WBC champion Deontay Wilder that would potentially have every major belt at stake.
"I'm not focusing on that anymore," he said.
"I'd had 22 fights and was talking about being undisputed. What am I going to do after? Go and fight Otto Wallin?
"It was like I was coming to the end of my road already, worrying about undisputed.
"I became heavyweight champion, I unified the division twice, and now my goal is to become two-time heavyweight champion of the world. Once I achieve that, I can look at becoming undisputed champion.
"That undisputed stuff? It was right in front of me but it was one of the biggest curses lingering over my head when I was champion."
Watch Anthony Joshua at his most brutally honest as he discusses his defeat to Ruiz Jr, the rematch and the conspiracy theories on AJ: The Untold Truth - On Demand from 6pm on Thursday, then on Sky Sports Main Event at 8.30pm on Saturday.