Former two division world champion David Haye, who manages heavyweight contender Derek Chisora, is keeping his fighter fully motivated on the upcoming fight with Oleksandr Usyk.
Usyk, the former undisputed cruiserweight champion, is taking part in his second career fight as a heavyweight.
Usyk made his heavyweight debut last October, when he stopped heavyweight veteran Chazz Witherspoon, who took the fight on very late notice and admitted he was exhausted, which forced him to stop fighting.
Chisora has been in some very tough fights in his career, where he had to gut it out and dig deep - in two twelve round wars with Dillian Whyte, making things very tough in fights with Robert Helenius and Vitali Klitschko, a come from behind knockout of Carlos Takam.
But Usyk has pretty much had his way with most opponents. His toughest fight was a decision win over Mairis Briedis in the World Boxing Super Series.
The fight between Chisora and Usyk takes place on May 23 at the O2 Arena in London.
Usyk is currently the WBO's mandatory challenger to unified world champion Anthony Joshua.
Haye cautions that Chisora must come for war, wear Usyk down and then take him out before the distance.
"Business is business. I’ve made sure he is not thinking about [any other fights] at all. It doesn’t matter, he has to find some way to drown Usyk. Who can drown the longest? I think Derek can, he has been drowning his whole career, gasping for oxygen, being out of shape, he is used to fighting on empty. Can Usyk fight on empty?," Haye said.