He spent the better part of his professional career with Real Sociedad, appearing in 153 competitive matches and spending six seasons in La Liga with the club.

A product of Basque Country giants Real Sociedad's youth system, Estrada was born in Zarautz, Gipuzkoa, and he spent his first two senior seasons with the reserves in the Segunda División B.

[1] Estrada made his debut with the first team on 10 February 2007, playing five minutes in a 2–1 home loss against Real Madrid.

[2] Three months later, in his third La Liga appearance, he was also brought from the bench against FC Barcelona (2–0 defeat, also at home),[3] and finished his first year with eight games in an eventual relegation.

In the following two Segunda División campaigns, Estrada was irregularly put to use at Real Sociedad, as they consecutively failed to regain their top-flight status.