Cristiano Ronaldo and Benzema have been at Real Madrid since arriving in 2009.
During that time they have struck up a stunning partnership, scoring 568 goals between them.
However, their form this season has waned.
Ronaldo has scored 19 La Liga goals but is six behind Barcelona's Lionel Messi in the race for the Pichichi award.
Cristiano Ronaldo believes Karim Benzema is past his best
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Cristiano Ronaldo and Karim Benzema have been team-mates since 2009
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Benzema, meanwhile, has netted just eight times in the league this season.
It has previously claimed that Ronaldo is a huge admirer of his Madrid team-mate.
Numerous Madrid stars are said to be worried about whether he has the mentality to still perform at the highest level.
Cristiano Ronaldo is jealous of the service Lionel Messi receives
A source said: "Even Cristiano has stopped believing in Benzema because he already gives less assists."
Ronaldo's anger at Benzema has reportedly led to him being jealous of Barcelona star Messi.
The Argentina international is the talisman of the team with Luis Suarez and Neymar his able deputies.
And Ronaldo feels Messi's success is down to those around him – and he reckons Benzema's failures are hampering his own chances of individual glory.