The 28-year-old joined the Bernabeu outfit in 2007 having spent seven years at Borussia Dortmund, making more than 120 league appearances for the Bundesliga side.
However, since arriving in Spain the German international has made just 21 la Liga outings for the Madridistas due to injury and, more recently, the form of Portuguese stopper Pepe.
And Metzelder has reacted angrily to the Bernabeu bosses' decision to splash out over £130 million on Kaka and Ronaldo, saying the inflated figures are wrong in the current financial climate.
"I don't know much about this evolution and I'm worried about it," he said in The Sun.
"Spending $96million on someone that can get injured or be in bad form isn't correct to me, especially during this period of financial uncertainty."
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