[3] Born in Oviedo, Óscar started his football career in his hometown club Stadium Ovetense [es], where he began playing as a goalkeeper by chance, replacing a teammate who had been injured during a match, and he soon demonstrates great qualities that made him stand out between the posts.
[4] Óscar was named the club's first-ever captain and he defended the Real Oviedo shirt from the first day of its existence until the Spanish Civil War interrupted football competitions in 1936.
[5] The regional Asturian team then played seven official games between 1922 and 1926 in the Prince of Asturias Cup, winning the 1922–23 edition,[6] largely thanks to Óscar's heroic performances in the semifinals, keeping a clean-sheet in a 1–1 win over Catalonia, which was mostly made-up of players of the so-called golden generation of FC Barcelona, such as Ricardo Zamora, Vicente Martínez, and Josep Samitier.
[8] Óscar was a member of the Spanish football squad that competed in the 1924 Summer Olympics, but he did not play in any matches.
[9] After another one-season stint at Real Avilés CF (1943–44), he gave up from coaching, but eventually returned following a 7-year hiatus to take charge of another Asturian team in the Segunda Division, Caudal Deportivo, and this time he lasted two seasons.