Manchester United star Ronaldo has revealed he is thinking of changing his approach to the game because of refereeing standards.

The Portuguese believes referees sometimes do not protect the skilful players in the Premier League.

The 23-year-old was making his comments after United controversially went out of the FA Cup to Portsmouth, losing their quarter-final 1-0 at Old Trafford thanks to a Sulley Muntari 78th minute penalty.

But referee Martin Atkinson failed to award United a first-half penalty following Sylvain Distin's foul on Ronaldo in the seventh minute.