Malik Scott who was in the klitschko camp that aj was a sparring partner for said Joshua "more than held his own" against klitschko 2 or 3 years ago and picks joshua to stop him. We can put the unsourced "klitschko beat him up in sparring" rumors to bed now
https://m.youtube.com/watch?v=w9uc2yrEgDw
https://m.youtube.com/watch?v=w9uc2yrEgDw