The veteran Brazilian joined in the summer from PSG on a free transfer.
He told Goal: "The choice to join Chelsea was not difficult. This is a club with a great history, its respected great jersey, our coaching team, above all the manager who has really succeeded here playing for Chelsea, and the club that really caught my attention in terms of quality of the team.
"With Chelsea my main goal is of course the Premier League. It would be a dream come true to win it and there is no doubt that we are looking to win the Champions League and the cups as well, so it's a matter of work. I think Chelsea don't just have 11 players."