Madrid's 3-0 first-leg win proved vital for them to reach the last four of the competition for the third season in a row with a 5-3 aggregate victory.
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The Portuguese forward came close to making it 2-0 moments later but was denied by a good Fernando Muslera save.
Madrid continued to dominate proceedings at the Turk Telekom Arena and had another good chance on 23 minutes, this time Muslera making a one-handed save from Angel di Maria's shot.
Ronaldo should have doubled Madrid's advantage on 56 minutes when he was found by Di Maria, but his effort from just yards out went wide.
That miss came to haunt Madrid immediately, as Emmanuel Eboue fired home from the edge of the box into the top corner to make it 1-1.
Then just after the hour mark Didier Drogba found Sneijder at the back post with the goal gaping, but the Dutchman dragged his shot well wide of the target.
However, Sneijder redeemed himself on 70 minutes when he slotted home past Lopez after getting the better of Raphael Varane and moments later Drogba found the target.
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Drogba had a goal disallowed for offside with 10 minutes left on the clock and Alvaro Arbeloa was sent off for Madrid a minute from full time, before Ronaldo's injury-time goal secured Los Blancos a place in the semi-finals.