Chimaev had been due to fight Robert Whittaker in Saudi Arabia at the weekend, but had to pull out as he was “violently ill” and was replaced by Ikram Aliskerov.

The New Zealander emerged victorious, and Chimaev could be an opponent for the middleweight when he recovers. 

Speaking to Crypto Sports Betting , Gustafsson suggested the root of the problem was his commitment in training.

He explained: “I can't even imagine how frustrated he is, I know he doesn't feel good at all. He's ill, he's very ill. Not only that, it's the mental part. You have a big fight ahead of you, it's the big card in Saudi Arabia and everything is on you, then this s*** happens.

“He trains so hard, it's inhuman the way he trains. But his illness is not because he overtrains, this is a whole different level of illness.

“The guy gets ill. There is something with his body that reacts to hard training because he is the hardest worker in the room, he's always been the hardest worker. They have to run some tests and see what the background is, whether there is something in his body that's reacting to the hard training because he trains very hard. I hope they find what it is and take care of the problem and he gets better.

“He very easily catches a cold for example – a running nose, coughing, symptoms that are not a big deal at all, we all get that. But I've seen when he increases his training a lot, I know his body reacts differently to the training. I don't know where it comes from. It's crazy how he reacts to the training these days.”

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