The Portuguese salvaged a draw for Jose Mourinho's team in the first leg after Danny Welbeck had given United the lead at the Santiago Bernabeu.
And Ronaldo hopes to put his name on the scoresheet again in his first return to the stadium of his former club, but is not sure how he would celebrate.
"It would be a beautiful sensation," he told reporters. "If I score against them, it would be spectacular.
|BACK TO HAUNT RED DEVILS?|
|4/1||Cristiano Ronaldo is 4/1 with BetVictor to score two or ore goals against Man Utd on Tuesday|
The 28-year-old expects to be well-received by the United supporters after winning three Premier League titles and lifting the Champions League once during a six-year spell in the north west of England.
"I'm sure they will receive me well," said Ronaldo, who is the European competition's current joint-top scorer with seven goals.
"After the years I spent there and the friendships I have, I'm sure it's one of the places where they'll applaud me most. It was a beautiful time."