A second-half goal by Brais Mendez gave Real Sociedad a 1-0 win away to Benfica that moved them above Inter Milan, who beat FC Salzburg 2-1 earlier on Tuesday, to the top of Champions League Group D on goal difference.
Both sides had first-half goals ruled out for offside and it took until the 63rd minute for Mendez to break the deadlock, scoring with a deflected effort from the edge of the six-yard box after great work by Ander Barrenetxea.
Benfica piled on the pressure late on and Fredrik Aursnes had a superb opportunity to level for his side in the 87th minute, but the midfielder snatched at his shot and made it easy for keeper Alex Remiro to save.
Real Sociedad top the group on seven points, with Inter second and Salzburg third on three points. Benfica are bottom with no points from their three games so far in the competition.