The 20-year-old arrived at Elland Road last month on a season-long loan deal from Flamengo, and Redfearn was impressed as he watched the Brazilian play for the club's youth squad on Monday.
"He did alright on Monday," the temporary boss told reporters. "He showed little glimpses of magic and his ability.
"He also showed a turn of pace when he tried to leave people. As an introduction I felt that it was good for him to play with our young pros.
"He is a tremendous young talent and he is a great signing for the club."
Adryan could make his full debut against Birmingham City on Saturday afternoon.