Anthony Joshua says he "does not want to get carried away with praise" after world heavyweight champion Wladimir Klitschko called him the most promising boxer he has seen "in 25 years".
Olympic champion Joshua has won all 13 of his professional fights.
"It's just potential. I've got to achieve it," the Watford-born 25-year-old told BBC Three Counties Radio.
"I've got to keep my head down and go and achieve what he believes and sees in me."
The Briton faces Scotland's Gary Cornish, who is undefeated in 21 bouts, for the Commonwealth title on 12 September, followed by a British title fight against Dillian Whyte in the winter.
Joshua visited the training camp of WBA, IBF and WBO champion Klitschkho prior to his fight with Johnson and said he found the experience very useful.
"It wasn't just to spar and come back. I wanted to learn, ask him some questions, see how his set-up was and that's exactly what I got," he added.
"It was more of a learning curve than an ego-booster."