Real Madrid's Cristiano Ronaldo celebrates his goal during their Champions League Group D soccer match against Ajax Amsterdam at the Amsterdam Arena stadium. (Photo: Reuters)
A dominant Real wasted a host of chances before Ronaldo pounced on a loose ball to score from close range in the 42nd minute and Benzema finished off a swift Real break three minutes into the second half when he smashed home a Kaka centre.
Real's vulnerability at set pieces gave Ajax hope in the 56th minute when Niklas Moisander stole in at the far post at a corner and nodded under Iker Casillas before Ronaldo scored twice in two minutes to kill off the game.
The victory consolidated Real's lead at the top of the group with six points from two matches as the record winners bid for the 10th European title that has eluded them since 2002.
With Sunday's La Liga 'Clasico' at arch rivals Barcelona looming, coach Jose Mourinho sprung several surprises in Real's starting lineup, deploying little-used Brazil playmaker Kaka instead of Mesut Ozil and Luka Modric.
In only his second appearance this season, Kaka showed some of the form that won him a World Player of the Year award in 2007, tormenting the Ajax defence and linking up well with Ronaldo and Benzema.
Ajax, coached by former Netherlands international Frank De Boer, looked a shadow of the side that has won four European titles and barely threatened Casillas's goal in the first half.
However, they fought back strongly in the second period as Real appeared to take their foot off the gas before Ronaldo, who scored three against Deportivo Coruna in La Liga on Sunday, completed his first Champions League treble.
Real and Ajax were meeting in the group stage for the third successive season, with the Spaniards winning home and away in 2010 and 2011.
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