Cristiano Ronaldo admits he could one day make a sensational return to Manchester United.

Ronaldo became a cult hero at United after enjoying six successful years under Alex Ferguson.

The Portuguese winger moved to Real Madrid for €100 million in 2009, but he still remembers his time at Old Trafford fondly.

Although he says he is happy at the Bernabeu, Ronaldo appears open to the possibility of going back to United in the future.

When asked about the possibility of playing for United again, Ronaldo told MUTV: “I love Manchester and you never know in football. Of course I’m happy at Real Madrid; it’s my home, it’s my club, but United treated me unbelievably, so you never know.

“I am still in contact with some people there because I had a good relationship with everybody — it was like my second family.”

Under Ferguson, Ronaldo won three Premier League titles and one Champions League before departing for Real Madrid for a then world-record fee.

United flopped spectacularly under Ferguson's successor David Moyes, who led the team to seventh — their worst-ever finish in the Premier League era.

But Ronaldo thinks United are now destined for success under their new manager Louis van Gaal.

“I think Van Gaal is going to do a fantastic job,” Ronaldo said in the interview, which was broadcast ahead of United’s friendly against Real Madrid in Michigan tonight.

A crowd of over 110,000, the largest ever to attend a soccer game in the United States, is expected to fill Michigan Stadium to watch the match although Ronaldo will miss the game through injury.