Ronaldo made his name at Old Trafford under Sir Alex Ferguson and in his six years won 3 Premier League titles, an FA Cup, a Champion’s League, and a Club World Cup, scoring 126 goals in 117 appearances.
"I will not celebrate my goal if I manage to score at Manchester United," Ronaldo insisted in an interview with AS.
He was sold by Sir Alex Ferguson in 2009 for £80 million and has since become one of the best players in the world at Real Madrid.
He spoke of him former manager in glowing terms, claiming the United boss was a father figure to him and revealed that he misses that bond.
"Like I said before, he's like a father in football. I really miss him and my relationship with him."
Ronaldo has recently been linked with a move back to Old Trafford, amidst turmoil at the Santiago Bernabeu.
Ferguson recently remarked that he would relish the opportunity to bring the Portuguese international back but admitted he now fears the 27-year-old is “unbuyable”.
One club that could challenge Ferguson’s belief is United’s rivals Manchester City, who the Guardian recently linked with a £134 million mega-swoop for Ronaldo and his Madrid and Portugal teammate Fábio Coentrão.
However, whether Ronaldo scores against his former club, it’s unlikely to make a difference to Sir Alex Ferguson, or United’s fans who would likely swap any sentimentality for a win over the Spanish champions and progression to the quarter finals of the competition.