Sir Alex Ferguson & Cristiano Ronaldo
Sir Alex Ferguson enjoyed a close working relationship with Cristiano RonaldoReuters

Cristiano Ronaldo was "petrified" to take David Beckham's number seven shirt at Manchester United. The Portuguese star joined the Red Devils in 2003 and has revealed he initially wanted to wear the number 28 instead.

However, Sir Alex Ferguson convinced Ronaldo – who was 18 at the time – to instead wear the iconic number seven, which was previously worn by the likes of Eric Cantona and David Beckham.

"When I arrived at Man United, I asked for 28 but the coach said no, you will wear seven," he said, according to The Sun. "I was petrified as I knew Beckham wore that shirt.

"But I took on the challenge and since then it has been my lucky number. I have won everything in football with that shirt."

Ronaldo, 30, admitted his career has subsequently become synonymous with the number seven jersey, which he has worn for Real Madrid and the Portuguese national team.

He said: "Everything I have is about the number seven. This is a story of the number seven. CR7 is part of my name now. Exactly."

Meanwhile, Ronaldo – who joined Real Madrid from Manchester United in 2009 – has recently been linked with a move away from the Spanish capital. However, Zinedine Zidane, the new manager of Real, has insisted Ronaldo will not leave the club while he is the manager.

Zidane said, as quoted by Marca: "It's not just that he isn't for sale. He's the heart and soul of this team. I laugh because as long as I'm here, he isn't going anywhere."

Ronaldo has been linked with a move back to Manchester United and manager Louis van Gaal has previously suggested he was interested in the player.

"Ronaldo plays on the wings and he is fast and scores goals. There is no trainer in the world that doesn't like him," Van Gaal said, as quoted by The Mirror. "Of course we are looking – but are looking at all players, not just Ronaldo. But these players are mostly ungettable. With Ronaldo, let's wait and hope."