Real Madrid punches win over Valencia
Benzema opened the scoring in the 37th minute of the first leg match, finishing off a rapid counterattack after Michael Essien had picked out Sami Khedira on the left flank.
Valencia missed its best chance of the match when Madrid goalkeeper Iker Casillas was forced to parry a powerful shot from Roberto Soldado straight toward an advancing Jonas, who fired just wide in the 67th.
Madrid's second goal arrived six minutes later when Valencia's Jose Guardado turned the ball into his own net as he tried to clear a cross by Fabio Coentrao under pressure from Gonzalo Higuain.
"It was a tight, physical match in which the goalkeepers kept the score down, although we came close to a third goal," Madrid defender Ricardo Carvalho said.
Cristiano Ronaldo won a free kick within 15 seconds of the start, but his subsequent shot flew just wide. Another effort seven minutes later soared over the crossbar.
Luka Modric shaved the outside of the post in the ninth minute having connected sweetly with Benzema's pass, as Valencia's goalkeeper Vicente Guaita stretched to reach the ball.
With the match initially locked in a tense midfield battle for possession, Valencia winger Jonas sent in a powerful header off Joao Pereira's cross in the 17th minute — only for Casillas to make a clean catch.
Jonas gave Casillas another fright when he hit a long shot which just skimmed over the top in the 35th.
Madrid coach Jose Mourinho adjusted his midfield by substituting Modric for Angel Di Maria in the 62nd and eight minutes later refreshed his attack by bringing on Higuain for Benzema.
The switch led to Madrid's second goal — but not without controversy.
Television replays showed Higuain may have just grazed the goal-bound ball with his hand, an action that caused vociferous complaints from Valencia's dugout and led to the dismissal of coach Ernesto Valverde.
"We were clearly hurt by some very poor refereeing decisions," Valverde said.
On Wednesday, Barcelona hosts Malaga and Atletico Madrid welcomes Real Betis, while Sevilla travels to Zaragoza on Thursday in the other quarterfinal clashes.