Cristiano Ronaldo has described former Manchester United manager Sir Alex Ferguson as an "unbelievable" person and the reason why he opted to move to Old Trafford.

After leaving Sporting Lisbon in 2003, Ronaldo scored 118 goals in 292 appearances during six seasons in England, and the Portuguese international is full of praise for the impact of his former boss, who spent £12.24m to take him to Manchester.

Speaking on The Jonathan Ross Show, the 30-year-old said: "It was the key why I [moved] here to England because I remember I had a conversation with him when we - Sporting Lisbon - played against Manchester and we had a quick chat and he told me, 'Listen I am interested in you, I want you to join us in Manchester.'

"It was the key, so he is an unbelievable person, the people don't really know him but I know. He's unbelievable, he [treated] me very [well].

"As I said many times, he is like a father for me in football. I have to appreciate what he did for me, I passed six seasons in Manchester very [well], I won many titles in terms of collective and individual. It was [an] unbelievable time for me here in England."

Since leaving United in 2009, Ronaldo has represented Real Madrid, where he has netted 326 goals in 315 games.