Ronaldo did not have the best record at the Etihad Stadium as a Manchester United player, scoring just once there from the penalty spot in May 2007 to all but win the Premier League for the Red Devils.
The 27-year-old was sent off in two of his last appearances at the stadium – in January 2006, a 3-1 win for City, and in November 2008, a 1-0 win for United.
However, Mancini thinks this record is insignificant, and is still concerned about the threat the Madrid forward poses to his side.
Asked how he intended to temper the Real Madrid striker’s threat, Mancini replied: “We’ll call the police.
“I just hope he can have a bad night on Wednesday because, when you come up against a player who can score one or two goals every game, it is difficult,” said Mancini.
“For him, it will be a big occasion, returning to Manchester, but it is an important night for Real as well, because they want to keep progressing towards the second stage.”
Mancini also believes that Ronaldo would be a worthy winner of the Ballon d’Or ahead of Lionel Messi in January, because his performances and goals fired Madrid to the league title last season.
“Ronaldo is a top player and he deserves to win the Ballon d’Or. He scored so many goals last year, and that helped Real finish above Barcelona in La Liga. He and Messi are the best players in the world, but what he did to make Real champions has to count in his favour.”
• City’s home record against Spanish clubs is W2 D1 L0. They overcame Villarreal CF 2-1 last season thanks to Sergio Agüero’s added-time goal.
• Madrid won 1-0 at Tottenham Hotspur on their last visit to England, Cristiano Ronaldo sealing a 5-0 aggregate win in the 2010-11 quarter-finals.
• Cristiano Ronaldo appeared in 11 derbies for United against City, winning seven and losing three. He scored four goals but was twice sent off at the City of Manchester Stadium.
• Twice a Spanish champion with Barcelona, Yaya Touré appeared five times against Madrid, winning three times and losing twice.
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