The 38-year-old came to terms with the Porto Alegre outfit on Tuesday after a meeting with the club's new president Fabio Koff.

"This is great news for Gremio. It is what the coach (Vanderlei Luxemburgo) and the club's board of directors wanted," Koff told Uol. Roberto spent a season at Real Madrid in 1997-98 before making a name for himself in Germany during spells with Bayer Leverkusen and Bayern Munich. He also played 84 matches for Brazil between 1995 and 2006.

Koff also revealed an interest in signing Argentina international midfielder Walter Montillo from Gremio's Brazilian rivals Cruzeiro.

"He is a very good player and Cruzeiro has said he could be up for sale," Koff said. "He won't be cheap but we are going to take a good look at the possibilities because we are interested in him. Gremio's ambitions are very big for 2013."