Seen as a more mature and less selfish player, Ronaldo has a chance to live up to comparisons with former Real great Alfredo Di Stefano as he faces United for the first time since the club paid 94 million euros to lure him to Spain in 2009.
Now 28, he made his name in England after joining from Sporting as an 18-year-old in 2003 and went on to win the World Player of the Year award five years later.
He has been in scintillating form since the turn of the year and warmed up for the United game with a hat-trick in a 4-1 destruction of Sevilla, earning a rousing ovation from the home faithful. It is a significant turnaround from a difficult patch earlier in the season when he raised eyebrows and prompted talk of an exit from the club by telling reporters he was unhappy "for professional reasons".
Ronaldo said it was not about money and he and the club now appear to have put it all behind them so he can focus on helping Real secure the 10th European crown that has eluded them since their last triumph in 2002.
"The Champions League is very special at Madrid because we want to win a 10th European title. For me it is the pinnacle," Ronaldo said.