Vela opened the scoring in the game, which would end up a seven-goal thriller.Carlos Vela scored a penalty kick in the 21st minute on Monday, but Real Sociedad couldn't hold the lead as it ultimately fell to a thrilling 4-3 defeat against Almeria.
The Mexican attacker's goal was his 11th league tally of the season, and 16th in all competitions. His career high for league goals was set last season with 14.
Sociedad appeared to have a share of the points, but Hicham Khaloua scored in extra time to ensure the hosts took the victory.
The loss was a big blow to Sociedad's Champions League hopes, as the side now sits in sixth place, nine points behind Athletic Bilbao in the fourth and final Champions League spot.