Sebastián Viera

International career Viera made his debut for Uruguay on 18 July 2004 in a Copa América quarter-final match against Paraguay, having been called as a late replacement for injured starter Fabián Carini. He also featured in the penalty shootout loss to eventual winners Brazil.

In five years, Viera earned 15 caps.

Coaching career Viera started working as a coach in the country where he had retired, being appointed at Primera B team Real Cartagena on 20 August 2024. Under his tenure, they reached the semi-finals of the tournament, missing out on a chance to play a promotion play-off by placing third in the season's aggregate table; he left by mutual agreement on 21 April 2025, following a 3–2 loss at home to Jaguares de Córdoba.

On 1 September 2026, Viera was appointed as head coach of his former club Junior.

Personal life Viera's father, also named Mario, was also a professional footballer and a goalkeeper.

Career statistics Club

Honours Nacional Uruguayan Primera División: 2005

Atlético Junior Categoría Primera A: 2011, 2018, 2019 Copa Colombia: 2015, 2017 Superliga Colombiana: 2019, 2020