Cristiano Ronaldo has said he will not celebrate if he scores for Real Madrid against his former club Manchester United after the two European heavyweights were paired together in the Champions League last 16.

Ronaldo left Old Trafford for the Bernabéu in the summer of 2009 after six glittering years at United during which time he won three Premier League titles and the Champions League playing for Sir Alex Ferguson.

He will face them for the first time in February's first leg at the Bernabéu, before returning to Old Trafford for the second leg in March.

"I won't celebrate if I score against United," Ronaldo told the Spanish newspaper AS. "I still speak with Ferguson. I miss him a lot, and I miss Manchester United. I felt very good there, it was like a family.

"I had six great years there and am still friends with my team-mates. It is thanks to Manchester United that I am here playing for Real Madrid. Without them, I wouldn't be the player I am today."

During United's victorious Champions League campaign in 2007-08, Ronaldo scored in both games against his former club, Sporting Lisbon, and did not celebrate either goal, also going on to apologise to the home fans after scoring the winning goal for United in Lisbon.

Ferguson said on Friday: "It will be fantastic to have him back," and joked: "It is in his contract he can't play against us. It would be a disgrace if he played."

He added: "When he comes on to the pitch at Old Trafford he will get a great reception, quite rightly. After that they can boo him as much as they like. You have to remember, he came here at 17 and developed himself into a great footballer.

"We are proud of the part we played in his career. To get six years out of a boy when he comes to us at 17, we have done very well."

Ronaldo will be celebrated despite eventually demanding to leave, the move to Madrid allowing him to fulfil a childhood ambition. "He always had a hankering to go to Real Madrid at some point in his career and we helped him on that way," said Ferguson.

"It wasn't disloyalty. I got another year out of him when he wanted go the previous year. He honoured that and did fantastic for us and then went with our blessing.

"My way of looking at it was that we were lucky to have him for six years. The United fans would share that."

Asked about his rivalry with Madrid's former Chelsea and Porto manager José Mourinho, Ferguson said: "I don't have a great record against him so we need to put that right."