Heavyweight contender Daniel Dubois admits that he was mentally affected by the referee's decision to rule his body shot as a low blow in the fifth round.

During the fifth, Dubois connected with a punch that immediately sent Usyk down in pain for several minutes. The referee, Luis Pabon, ruled it as a low blow.

Several replays of the punch would create a lot of controversy and confusion, because there were many observers who felt Dubois connected with a legal blow or a borderline shot. However, there were also many who felt the punch had strayed low and Pabon made the right call.

During that sequence, Dubois explains that he became confused when he saw Usyk go down and no count was issued from the referee.

"From then on, when he went down I thought 'OK, now the 10 count'. I knew he wasn't going to get up in time. He was holding his stomach. He couldn't move," Dubois told BBC Sport.

"But something in me just felt 'oh no, what's going on in here? This isn't right. Why isn't he being counted?' I'm looking ringside at what's going on, I see all craziness.

"I was thinking 'what's going on here, this is a blatant shot.' I told the referee I caught him and it wasn't low. It was just confusion at the time. I became disheartened and lost momentum after that, having to come back into the fight and try to push it.

"I was up against it, on enemy territory, but I wasn't out of my league. If that was in England that would be totally different. Circumstances make a big difference - home turf, home advantage."

Usyk would eventually recover from the punch. He knocked Dubois down from a combination of punches at the end of the eight round. The end came in the ninth, after a right hand sent Dubois down for the full count.