He is the youngest player and goalscorer in the history of Athletic, having made his debut – and scored – in the Campeonato Regional Norte on 18 October 1914, at the age of 16 years, four months and 12 days.[4][5] He had not been registered officially as a player with Athletic for the requisite six months, and the club were sanctioned by the federation.[1] His records have sometimes been overlooked and the feats attributed incorrectly to Agustín Gaínza (and subsequently to Iker Muniain).[6]
Acedo is also the club's youngest player and scorer in the Copa del Rey having found the net on his debut in that competition on 25 April 1915, aged 16 years, 10 months and 19 days (neither Muniain nor Gainza played in the cup before turning 17).
On 28 August 1920, Otero was among national team history as one of the eleven footballers who played in the first game of the Spain national team for the 1920 Summer Olympics, in an eventual 1–0 victory over Denmark.[7] He featured in three more games at the tournament, scoring the winning goal against Sweden and starting in the play-off for the silver medal against the Netherlands, which Spain won 3–1.[8] In total, he earned 11 caps for Spain between 1920 and 1924, scoring 1 goal.[9]
With Athletic playing in the local league, he was summoned to play for the Biscay autonomous football team, and was a member of the team that participated in the 1922–23 Prince of Asturias Cup, an inter-regional competition organized by the RFEF.[10][11] In the quarter-finals against Asturias on 13 November 1922, Acedo imprinted his name in the competition's history with an late equaliser in extra-time to level the scores at 2–2 and force a second extra period in which Asturas prevailed as 4–3 winners.[12]
Domingo Acedo's older brother Aquilino also played for Athletic Bilbao just prior to his younger sibling's debut; in his brief career he featured in the 1913 Cup final defeat to Racing Irun, and in the inaugural match at San Mamés stadium against the same opposition (now renamed Real Unión), before retiring through injury.[13][14]
^Vicente Martínez Calatrava (17 August 2009). "La Copa Príncipe de Asturias" [The Prince of Asturias Cup] (in Spanish). CIHEFE. Retrieved 26 June 2022.
^"De Acedo a Bilbao: claros del bosque" [From Acedo to Bilbao: clearings of the forest]. Memorias del Fútbol Vasco (in Spanish). 11 March 2012. Retrieved 23 September 2017.