The 33-year-old is set to sign a two-year contract with the Greek side and will join the club on a free transfer after his contract with Villarreal expired.
The Argentinean said to Greek sports site The Player: “It’s true that my first choice was Olympiakos.
“Since the beginning of the negotiations I told my agents to do everything possible in order to go to Greece.
“I was told by my agents a few hours ago that everything is OK and I can say that I am very happy to go to Greece to such a big club as Olympiakos. They are the biggest Greek club.
“My target is to help the team to win the title and to do something really good in the European competitions. I will try my best for Olympiakos.”