He was quoted in yesterday's press that a deal with Juve was close.
"I have certainly not signed for Juventus," the Belgium international tweeted. "I didn't speak about my President either.
"I didn't say that I am leaving. They simply wrote what they wanted to write. All I said was that it was an honour to be tracked by a great club.
"Don't believe what has been said. I can say with tranquility that I am still a Cagliari player and that I have spoken to nobody.
"There is no contract already prepared. None of this is true "