Cristiano Ronaldo could return to Manchester United after reportedly saying he wants to leave Real Madrid.Following the stunning revelation that he has asked to leave the Santiago Bernabeu, former Real Madrid president Ramon Calderon has suggested Cristiano Ronaldo could now return to Manchester United.According to a Portuguese tabloid, A Bola, Cristiano Ronaldo has informed Real Madrid president Florentino Perez that he wants to leave the club this summer.The 32-year-old was recently embroiled in a tax complaint from Spanish prosecutors who alleged that he evaded €14.7 million (£13m) in tax and it has left the four-time Ballon D’Or winner outraged.And Calderon has now suggested the Portuguese could be set for a sensational return to Old Trafford, from where he moved to Real in 2009.Read also: The 5 players who could replace Ronaldo at Real Madrid"I think it is very difficult. I had the same situation with Manchester United when he wanted to leave and I signed him. He said 'I want to leave' and that was that," Calderon told BBC Radio 5 live."The same year I had the problem with Robinho and he wanted to leave."As a president you can't do anything other than let him go and get the best deal possible."I hope he hasn't decided to leave but if he has already made his mind up, it will be difficult to change the situation.Calderon admitted a return to United could be on the cards, where he would link up with former boss Jose Mourinho."Very few clubs can meet his expectations. Not because they can't pay the money but because they need to offer him the possibility of winning titles and personal awards," he added.