The young Frenchman earned his second game-winning goal of the season against a Los Che side that had already secured third place in the Primera Division standingsA goal in the second half from Antoine Griezmann carried Real Sociedad to a 1-0 win over Valencia on Saturday in their final Liga game of the 2011-12 campaign.
The young winger, who also scored the winner in the reverse fixture earlier in the season, managed to capitalise on a sleeping Los Che defence to end the season on a high note, while Unai Emery's four-year stint at the Mestalla outfit finished in defeat.
The Basque coach sent out his fringe players at Anoeta for his last game before Mauricio Pellegrino takes over the helm. In the opening 40 minutes of the contest, neither team could create a quality chance on goal, other than an isolated opportunity from Aritz Aduriz in the opening minutes, which failed to find the target.
The defenders marked out their attackers and the goalkeepers were alert as the first half rapidly passed with nothing to show from either side, until Aduriz wasted a close chance two minutes from the break, trying a chip from inside the box that was not even close.
After the interval, Pablo Hernandez nearly put the visitors ahead just four minutes in with a left-footed blast from the left side of the box, which Claudio Bravo saved with a reflex dive. Seconds later, Aduriz had one of his side's best attempts after Sofiane Feghouli did well down the left to get free, sending in a curling cross that found the veteran attacker six yards out, but the ball was headed wide.
On 58 minutes, Carlos Vela got free down the left and whipped in a well-placed delivery to the far post. Retiring captain Mikel Aranburu headed the ball with power but Diego Alves was there to push it wide.
After the goalkeeper produced another fine save moments later from Daniel Estrada, the Brazilian was eventually beaten. On 64 minutes, Griezmann found the net with a clever sliding effort at the near post, connecting with a ball from Xabi Prieto on the right.
Both teams attacked in the remaining minutes but neither could add to the score, with the hosts earning a well-deserved victory.
Valencia finish La Liga in third with 61 points and automatic Champions League qualification, while Real Sociedad provisionally sit in 12th with 47 points, but will be guaranteed a finish of no lower than 14th after the rest of the fixtures on Sunday.