AJ, 32, lost his trio of heavyweight titles after being stunned by Usyk at the Tottenham Hotspur Stadium in September.
The Brit is desperate to get his belts back after only the second loss of his career with the rematch slated for some time early next year, according to his promoter Eddie Hearn.
But Usyk’s manager Sergey Lapin insisted his former sparring partner still has plenty of tricks up his sleeves.
“I have known Alexander for more than 20 years,” Lapin told MyBettingSites.
“I have been there and seen all of his successes in boxing.
“One thing that sets him apart is he processes information and adapts to the fighter in front of him very, very quickly. It sometimes seems to me that he is from another planet – he is that good.
“Despite the fact that he has a huge amount of experience and fights behind him, he is constantly improving and getting better every training day.
“I have seen and know what Usyk is really capable of, and the version of Usyk in the fight with Anthony Joshua was 60-70 percent of his potential.
“So yes, Usyk can really be better.”
But Usyk 17 CEO Lapin also admitted he was impressed by Joshua’s performance despite the former world champion almost being finished in the last few seconds of the fight.
He recalled: “To be honest, in the fight with Usyk, I saw the best version of Joshua in years.
“Joshua is strong-willed and has character. All belts were at stake, and he went all-in, but lost.
“I don’t understand at all why most boxing skeptics say Joshua’s wrong strategy was the explanation for Usyk’s victory.
“This victory was not just a lucky blow, as in the fight with Ruiz, it was a victory by all criteria.
“As for the immediate rematch, right after the end of the 12th round, I heard Anthony say: “Hey, Alex, I know how to beat you, I want a rematch”.
“Now he will try to take back his title. We are definitely looking forward to a very cool rematch.”