The 30-year-old played began his senior playing career in 2008 with Defensor Sporting in his hometown, Montevideo, where he also represented Liverpool FC of the Uruguayan Primera Division. He spent a season on-loan with Romanian club Dinamo Bucuresti, besides which he represented CD Badajoz in Spain, Montevideo Wanderers and Atletico Rafaela in Uruguay.
On completiong of the signing, FC Pune City CEO Gaurav Modwel said, "Martin will strengthen our defence with his vast experience in South America, Europe and of course an entire season in ISL. He is versatile and can play either as centre-back or a defensive midfielder. He is technical and is good with playing the ball from the back, which suits our style of play."
Pune City head coach Miguel Angel Portugal commented, "I have seen Martin last season and what impressed me is his work ethic and adaptability. He is never short of energy and brings in a lot of experience, which will help the young players of our team. I welcome him to our club and hope he makes a positive impact on the club as well as its fans."
Diaz, on his signing, stated, "After witnessing what FC Pune City achieved last season, I felt the club was really moving along well. After meeting them, I realised their professional approach to everything in and around the club helped them achieve what they did. I am excited to join my new team and equally thrilled about accepting this new challenge."