In October 1913, a friendly was held between the two teams to inaugurate Real Sociedad's Atotxa Stadium; the result was a 3–3 draw and the first goalscorer at the stadium was Pichichi, Athletic's legendary forward of the age who had also been the first scorer in the opening match at Athletic Bilbao's own new ground, San Mames, two months earlier. In the same year, regional league competitions were introduced to the area to determine the qualifying teams for the Copa del Rey. In the first three seasons, Athletic Bilbao and Real Sociedad were in the same competition, but due to repeated disputes by the rival provinces, these separated into the Biscay Championship – dominated by Athletic and Arenas Club de Getxo – and the Gipuzkoa Championship – usually won by Real Sociedad or Real Unión – which ran in parallel for sixteen years.
