Debut semi-finalists Manchester City welcome Real Madrid, who are making their 27th appearance at this stage, but have already registered two wins against Spanish sides this season.
The UEFA Champions League semi-finals have stirred up memories for Manchester City and Real Madrid's star strikers, both of whom know their last-four rivals very well indeed. With Manchester United, Ronaldo played City in 11 derby matches, while Sergio Agüero represented Atlético in 11 such games with Real Madrid. UEFA.com picks out the key statistics.
Ronaldo's English meetings with City
P11 W7 D1 L3 (W4 D1 L1 at home, W3 D0 L2 away), goals: 4
Goals-per-game ratio for United: 0.43 (234 domestic league and cup games, 101 goals)
Goals-per-game ratio against City: 0.36 (11 domestic league and cup games, 4 goals)
Key highlights
• Ronaldo scored his first cup competition goal – and only his second in all competitions for United – against City in a 4-2 FA Cup home win on Valentine's Day 2004.
• He was sent off for the second time in his United career during a 3-1 Premier League defeat at City in January 2006, for a rash challenge on former United ace Andrew Cole.
• Ronaldo notched his first Premier League goal against City in a 3-1 home success in December that year; his was the late third, the Portuguese having also set up Wayne Rooney's opener.
• On 5 May 2007, Ronaldo registered his 50th goal for United from the penalty spot in a 1-0 triumph at City; a draw between Chelsea and Arsenal the next day confirmed United as English champions.
• Ronaldo received the fourth and final red card of his United career against City in November 2008, picking up a second yellow in odd circumstances for handling a Rooney corner.
• Ronaldo said he had heard the referee's whistle and "took the initiative to stop the match". Sir Alex Ferguson said he was "trying to protect himself from the ball hitting his face". City boss Mark Hughes responded: "If it was going to hit him in the face, why didn't he head it?"
• Ronaldo netted his last United goal in a 2-0 home victory against City in May 2009 – a deflected free-kick – though his angry reaction to being substituted overshadowed his strike.
• United beat City in every meeting in which Ronaldo scored.
• Ronaldo also scored once as Real Madrid beat City 3-2 at home in the 2012/13 UEFA Champions League group stage, but did not register in the return fixture – a 1-1 draw.
Agüero's Spanish meetings with Madrid
P11 W0 D3 L8 (W0 D1 L5 at home, W0 D2 L4 away), goals: 3
Goals-per-game ratio for Atlético: 0.42 (195 domestic league and cup games, 81 goals)
Goals-per-game ratio against Madrid: 0.27 (11 domestic league and cup games, 3 goals)
Key highlights
• Atlético lost to Real Madrid in every encounter in which Agüero scored; he has yet to win a match against the Merengues.
• Agüero hit the opening goal of the 2007/08 Liga campaign as he nodded home inside the first minute at the Bernabéu. Ultimately, however, he finished on the losing side as Madrid came back to prevail 2-1.
• He got two more goals against Madrid: he eluded Pepe to pull one back in a 3-2 home loss in November 2009, and also reduced the deficit after playing a one-two in a 2-1 home reverse in March 2011.
• Agüero started nine of the 11 games in which he participated against Real Madrid.
• The forward was linked with Real Madrid last summer, before electing to sign a new deal with City: "The only reason a player should leave a club is to achieve things, and I can achieve all I want to at City," he said.
• Rumours his transfer to City had included a clause forbidding Agüero from moving on to Real Madrid proved unfounded, though he was quoted as saying: "I had great times [with Atlético] and couldn't betray them by signing for Real Madrid."
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