He appeared in 267 La Liga matches over nine seasons, scoring a combined 40 goals for Valladolid (two spells) and Zaragoza.

Born in Salamanca, León, Óscar began his career with Real Valladolid, making his first-team – and La Liga – debut in the 1–0 home win over UD Las Palmas on 7 October 2001, one month shy of his 19th birthday.

[1] Establishing himself as a regular by the start of the 2002–03 season, he was the side's best scorer in the following year at 10, in spite of a final relegation.

on a three-year deal during the summer transfer window, joining countryman Ernesto Valverde's roster.

[5] On 1 September 2010, Olympiacos parted ways with Óscar, who signed a one-year contract with his first professional club Valladolid, now playing in the Segunda División.