The Brazilian gloveman was snapped wearing the Blues strip at a fancy dress party for Luiz's birthday in London, attracting the ire of R's supporters.
However, the former Inter Milan man insists it was only in jest and has apologised for causing any offence to the Loftus Road club.
"I would like to clarify that last night I attended David Luiz's fancy dress birthday party and as a joke for my friend, my family and I dressed as him," Cesar said in a statement on QPR's official website.
"I want to assure everyone that absolutely no offence was intended."
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