Nguyễn Trung Sơn

Marcos Jeferson Farias Valentim (born 29 January 1982), also known as Nguyễn Trung Sơn, is a Brazilian former footballer who played as a midfielder.

After retiring from professional football, he worked at a hotel in Brazil.

Valentim was born and raised in Brazil, where he had a wife and children. He later became a naturalized Vietnamese citizen and married a Vietnamese woman.