DEONTAYWILDER struck Isaac Chamberlain so severely that he believed he was back at London.
Chamberlain, a cruiserweight, sparred with the former heavyweight world champion as a teenager.
Isaac Chamberlain photographed with Deontay Wilder, his former sparring partner
Wilder was in preparation for his 2015 title win against Bermane Stiverne.
Chamberlain was the recipient of one of the greatest right hands in boxing history.
Sky Sports reported that he said: "He is powerful, very powerful.
"I can recall sparring him when I was 19 years old, he hit me with an elbow and I thought I was back home in London. He is a strong puncher.
It's always his power. It's not his power, it's his speed. He is very fast and can process very quickly.
People don't realize it, and they think he is wild in general. He's not wild if he gets you hurt.
He is very, very sharp and sticks to the basics. He's more than people think.
"There is a method behind all madness."
Wilder's brutal power was unstoppable, and no one knew how to stop him until Tyson Fury faced him in 2018. The match ended in a draw.
However, Fury (33), won the subsequent rematches by KO. The last one kept Wilder (36) on the sidelines.
This year, the American will be making a comeback and will face Robert Helenius (38).
Chamberlain, who is 28 years old, will face Chris Billiam Smith, 31 on Saturday. Wilder will be back to defend the ring.
He stated: "One million percent . We need characters like this in boxing, we'll be back.
"I can remember FaceTiming him before any other fights. He was in the zone and locked into.
"Recovering from an injury is a true test of character."
Isaac Chamberlain supported Deontay Wilder's return to the ring
Deontay Wilder will make his boxing comeback this year
