The Mexican striker bagged his 14th league goal in his spell with the Spanish outfit, a penalty strike against Bielsa's Bilbao.
Carlos Vela put Athletic Bilbao away on Saturday after just three minutes on the field, scoring a penalty kick goal that lifted Real Sociedad's advantage to two goals in the second half.
Vela was designated to take the spot kick following Amorebieta's infraction one minute earlier, which resulted in the Bilbao player getting a second yellow card and putting Athletic down to 10 men.
Antoine Griezmann had made it 1-0 for the home team in the 62nd minute, with Vela's penalty kick strike widening the gap beyond the reach of the visitors.
The Mexican striker has scored twice this season from the spot, with his first goal coming against Zaragoza following another infraction in the penalty box. Vela has scored a total of 14 league goals for Real Sociedad since joining the team originally on a loan basis from Arsenal in 2011.
With the win, Real Sociedad temporarily pushed up to sixth place in La Liga, climbing up to nine points in six matches.