The 29-year-old, who joined Atletico on a short-term deal in January, is believed to be attracting interest from former club Santos, and his father claims that a move is a possibility at the end of the season.
"The interest is mutual, there is a big chance of him returning to Brazil," Djair Ribas told Globo Esporte. "Other Brazilian clubs are interested, but he prefers Santos.
"We will wait until the last games to talk, Diego is under contract with Atletico Madrid and a lot of things can happen."
Diego started his professional career with Santos before moving to Porto in 2004.