Real Madrid signing Cristiano Ronaldo says he quit Manchester United, in part, due to the kicking he received during Premiership games.

He said: "There are some teams who know they can't compete with you on a football level, so they just kick you.

"It's frustrating and something needs to be done to protect the skilful players because one day someone will get seriously hurt. I think more could be done to protect us but that is up to the referees to decide."