[1] In the late 1890s, Martínez de las Rivas began playing football with an informal group led by Carlos and Manuel Castellanos, the so-called Bilbao Football Club, the first entity to play football in Bilbao since the disappearance of Club Atleta, a multi-sports club that mainly consisted of the British workers of the Nervión Shipyards, which had been founded by his father in 1889.
[2][7] Rivas then played some friendly matches for them against city rivals Athletic Club in the Hippodrome of Lamiako, which at the time was the home of organized football in Biscay.
For instance, on 15 December 1901, he played for Bilbao FC as a defender alongside Enrique Careaga, keeping a clean-sheet in a 2–0 victory.
[1] In 1905 he participated in the regattas of Kiel, with Enrique Careaga's sloop Princesa de Asturias.
[1] In 1904, Martínez de las Rivas returned to the club's presidency, and in the following year, he visited King Alfonso XIII, who showed him the desire to create a regattas Cup in Bilbao, with the Real Sporting Club in charge of writing the regulations.