Napoli have been chasing Rafael for most of the summer with reports suggesting Morgan De Sanctis could leave the San Paolo for Serie A rivals Roma.
The 23-year-old admits that the chance to play in Europe and the Champions League for Napoli persuaded him to leave Santos.
"I always thought I would finish my career here at Santos," said Rafael. "But with the passage of time I realised that I wanted to play in Europe and in the Champions League.
"But that does not mean that one day I will come back and finish my career at Santos."