WBO welterweight champion Terence Crawford has warned MMA star Francis Ngannou that he's making a big mistake by calling out two of the elite at heavyweight - Tyson Fury and Deontay Wilder.

For some time, Ngannou has been pressing to make his debut in professional boxing - by taking part in a major event against Fury or Wilder.

Ngannou wants to replicate the 2017 mega-event between Floyd Mayweather and Conor McGregor.

The man who previously held the UFC heavyweight title was initially precluding from boxing by UFC President Dana White. Last year, Ngannou parted ways with the UFC and only recently signed an agreement with rival organization PFL.

Ngannou has no intention returning to MMA until next year - because he wants to make his boxing debut in 2023.

Crawford credits him for having power, but feels he's not skilled enough, or experienced enough, to present a threat to Fury or Wilder in a boxing ring.

“Listen, that guy is a puncher. He’s doing his thing in MMA, but it’s different over there, calling out the top heavyweights of the world today. I don’t see him having a chance with either one of those guys, and that’s just being honest," Crawford told The MMA Hour.

“He’s got some skills. I would tell him, get your feet wet, try to fight some of those lower-tier guys first, just to feel yourself out, and get used to being in the ring, going rounds. It’s different. MMA and boxing are different. So just get used to some people with skills coming back at you and out-thinking you, the whole realm of boxing, before you go over there and try to mess with those guys. Because one guy that you’re going to get one shot — and if you mess up, you’re going to be knocked out into next week for messing with — [is] Deontay Wilder.

“If he hits you, you’re going to sleep. Deontay Wilder, he hits you, you’re going to sleep. Tyson Fury, he went to sleep and woke up. I don’t see too many other guys doing that. Deontay Wilder is one of the biggest punchers ever, so just keep that in mind.”