The Argentina international joined from Napoli earlier this month in a deal believed to be in the region of £23.7 million.
Pastore himself made the move from Serie A to France 12 months ago, having signed from Palermo.
And the 23-year-old expressed his joy at his compatriot’s arrival at the Parc des Princes, and is excited about playing alongside the former Estudiantes man.
"I'm very happy with his arrival because he is a friend of mine," he told the club's official website.
"I got to know him in the national team, and his coming here has made me very happy. It's certain that he will bring us a lot going forward, and that is decisive for us.
"We know that he has great potential and that he will be an added asset to us."
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