|Full name||Agustín Gaínza Vicandi|
|Date of birth||28 May 1922|
|Place of birth||Basauri, Spain|
|Date of death||6 January 1995(aged 72)|
|Place of death||Basauri, Spain|
|Height||1.72 m (5 ft 8 in)|
|* Senior club appearances and goals counted for the domestic league only|
Nicknamed Piru, Gaínza's entire career was spent with Athletic Bilbao. Born in Basauri, Biscay, he made his official debut and scored in a Biscay Championship match on 15 January 1939 against SD Erandio Club, aged 16 years, seven months and 18 days. This made him the club's second-youngest debutant (behind Domingo Acedo in 1914), a statistic which lasted until 2009 when Iker Muniain surpassed the appearance record by seven days and equalled the scoring one the following week.
Gaínza made his La Liga debut on 13 October 1940 in a 1–0 away loss against Hércules CF, then proceeded to play a total of 19 seasons in the competition with the same team, amassing totals of 380 games and 119 goals. During his spell with the Lions of San Mamés he won nine major titles, including two national championships and seven Copa del Generalísimo trophies, plus a Biscay Championship and a Copa Eva Duarte (supercup). In May 1958, he received a testimonial match against English side West Bromwich Albion; coincidentally, the only goalscorer was Ronnie Allen who later became head coach of Athletic and organised further benefit matches between the clubs.
Gaínza retired at the end of the 1958–59 campaign at the age of 37, having appeared in 494 official matches which was a club best at the time of his retirement. Such was his length of service that in addition to being one of its youngest goalscorers he was also the oldest, having found the net for the final time against Sevilla FC in March 1959, aged 36 years and 298 days; that record stood for 58 years, until Aritz Aduriz surpassed it in December 2017.
Gainza also set several Spanish Cup records: he won seven editions, appeared in nine finals, played most for one club in the competition (99 games), and was the highest scorer in a single match, having claimed eight goals in a 12–1 victory over Celta de Vigo in the 1947 quarter-finals after a 1–0 loss in the first leg.
Gaínza won 33 caps for Spain, scoring ten goals. He made his debut on 11 March 1945 in a friendly against Portugal and, as with Athletic, was team captain in the 1950 FIFA World Cup as the country finished in fourth position.
Gaínza's older brother, Miguel (1920–86), was also a footballer. A defender, he too played for Athletic Bilbao, and also for Barakaldo CF. It was reported that as a child Agustín was not interested in football and had to be encouraged to play the game by Miguel, and even when approached by Athletic in his teens was reluctant to take it up as a career, with his brother persuading him to agree terms.
Two bronze busts of Gaínza were created by the sculptor José Manuel Alberdi in 1997. One was displayed outside his family home in Basauri (having been donated to the town by the local supporters' club), and the other was situated at the Athletic Bilbao training headquarters at Lezama.
Gaínza died on 6 January 1995 in his hometown, at the age of 72.
- La Liga: 1942–43, 1955–56
- Copa del Generalísimo: 1943, 1944, 1944–45, 1949–50, 1955, 1956, 1958; runner-up 1948–49, 1952–53
- Copa Eva Duarte: 1950
- "Iker Muniain, con 16 años, se convierte en el segundo jugador más joven en debutar con el Athletic" [Iker Muniain, 16, becomes the second youngest player to debut with Athletic] (in Spanish). Europa Press. 31 July 2009. Retrieved 27 July 2017.
- "Muniain se cita con la historia" [Muniain has an appointment with history]. Mundo Deportivo (in Spanish). 30 July 2009. Retrieved 30 July 2017.
- "Agustín Piru Gaínza, el gamo de Dublín" [Agustín Piru Gaínza, the fallow deer of Dublin]. Marca (in Spanish). 7 October 2016. Retrieved 5 November 2017.
- "Leyendas del Athletic Club de Bilbao – 'Piru' Gainza" [Athletic Club de Bilbao legends – 'Piru' Gainza]. El Correo (in Spanish). Retrieved 23 May 2016.
- Matthews, Tony (2015). Baggies Abroad: The Complete Record of West Bromwich Albion's Global Travels. Pitch Publishing. ISBN 9781785310997.
- "Results 1957–58". Albion Till We Die. Retrieved 5 November 2017.
- "Ingleses y alemanes (El Athletic en Copa de Ferias y UEFA, pt VI)" [English and Germans (Athletic in the Fairs and UEFA Cups, part VI)]. El Correo (in Spanish). 20 September 2009. Retrieved 27 July 2017.
- "Aduriz, tercer goleador más veterano del Athletic en Liga" [Aduriz, third-oldest goalscorer for Athletic in League] (in Spanish). El Desmarque. 20 March 2017. Retrieved 30 July 2017.
- "Aduriz, el jugador más veterano en marcar con el Athletic en Liga" [Aduriz, the oldest player to score with Athletic in League]. Marca (in Spanish). 10 December 2017. Retrieved 20 May 2018.
- "El genuino rey de Copas" [The true king of Cups]. El País (in Spanish). 12 May 2009. Retrieved 5 November 2017.
- "Historias de la Copa: El día que Gaínza marcó 8 goles" [Cup stories: The day Gaínza scored 8 goals] (in Spanish). Royal Spanish Football Federation. 7 February 2015. Retrieved 27 July 2017.
- The high before Brazil’s biggest low; FIFA, 29 June 2013
- "Gainza: Miguel Gainza Vicandi". BDFutbol. Retrieved 19 November 2013.
- "Miguel Gainza". Athletic Bilbao. Retrieved 5 November 2017.
- "Monumento a Piru Gainza" [Monument to Piru Gainza] (in Spanish). Basauri Municipality. Retrieved 30 July 2017.
- "Mikel Vesga, el timonel del Sporting" [Mikel Vesga, the helmsman of Sporting]. Mundo Deportivo (in Spanish). 23 March 2017. Retrieved 30 July 2017.
- "Un gamo de mirada zurda" [A deer with a left gaze]. El País (in Spanish). 7 January 1995. Retrieved 6 August 2017.