The pair played together at Manchester United.
“He'll do what he's been doing for the last 10 years, he'll bring goals to Juventus," Rooney told CNN.
“I fancy Juventus to win the Champions League this year solely for the fact Cristiano has gone there.
“As a person he's a nice guy, a family guy, works hard and he's always got his family around him which is great to see.
“He works hard and deserves all the credit he gets because he's put that effort in to be at the top."