Cristiano Ronaldo's release from Manchester United's restrictions on his commercial activities could earn him over £85 million. The Observer has reported that Manchester United boss Sir Alex Ferguson is reluctant to let his players exploit their commercial potential.

Commercial and licensing rights expert Mary-Ellen Field said, "Ferguson's view that (commercial exploitation) takes a player's mind off the game is valid.

"However, the contract between the player and licensee means they usually have to work 20 days a year at most.

"With any brand building, whether it's a person or product, the more positive exposure you get, the more valuable your brand becomes. It would have been beneficial for the club and player to get as much exposure as possible."

The paper predicts Ronaldo will be encouraged in the opposite direction at Real Madrid.

Simon Chadwick, professor of sport business strategy and marketing at Coventry University, said, "United have a greater desire for on-field performance, driven by Ferguson. From the people I speak to at Real regularly, there is a much greater sense that Madrid is an entertainment brand rather than a football club."