Nicolás Fonseca was born on 19 October 1998 in Naples, Italy, in a Uruguayan football family. The son of Daniel Fonseca, he grew up with Italian formation and Uruguayan identity.
He passed through Novara and River Plate Montevideo before River Plate of Argentina signed him for 2024. Buenos Aires demanded bravery in possession and defensive control from the holding role.
In January 2026 he joined Real Oviedo on loan from León. Spanish football gave him another setting after Italy, Uruguay and Argentina.
For Uruguay he entered the senior setup during Bielsa's period. The midfield hierarchy is hard, but his passing confidence and defensive base keep him in the conversation.
Around 1.81 m and right-footed, Fonseca is a defensive midfielder with a composed first pass and willingness to tackle. He has Lucas Torreira's competitive edge in a taller frame.