A lacklustre Atletico Madrid failed to consolidate second place in La Liga after falling to a 3-0 defeat to Real Sociedad at the Anoeta Stadium on Thursday evening.
The home side deservedly opened the scoring in the 27th minute when Willian Jose smashed Adnan Januzaj's cross past Jan Oblak from 12 yards out.
Imanol Alguacil's side continued to dominate the woeful visitors in the second half and doubled their advantage in the 80th minute when Juanmi chipped an excellent effort over Oblak before the Spaniard scored his second and Sociedad's third with a fine header seconds from time.
The hosts started the better of the two teams and carved out the first opportunity of the game in the 12th minute. Alberto De la Bella drove down the left channel before he squared the ball to Willian Jose inside the box 12 yards out, the striker tried to get a shot away but was denied by an excellent challenge from Diego Godin.
Sociedad continued to press Atletico and had a number of chances to take the lead on the quarter-hour mark. De la Bella's whipped cross from the left created a mad scramble inside the box but the ball was eventually cleared.
Canales then had a shot from distance blocked, the ball fell to Willian Jose who went down inside the box but the referee quickly waved away the half-hearted penalty appeals.
Atletico had their first chance of the half in the 22nd minute. Godin got to Koke's corner delivery first but his header from six yards out was easy enough for Rulli to claim.
La Real took a deserved lead in the 27th minute. Former Manchester United midfielder Adnan Januzaj's scuffed cross from the right found its way to Willian Jose on the penalty spot, the Brazilian struck a powerful low shot which smacked off the post and past a statuesque Oblak for the opening goal of the game.
As half time approached, the home side continued to look the more threatening and especially down their right side through Januzaj. The 23-year-old nearly doubled his side's advantage a minute before the break with a rasping shot from 25 yards which just drifted wide of Oblak's right-hand post.
Los Colchoneros had looked ponderous throughout the first 45 minutes and Diego Simeone decided to make an immediate change at half-time, as Ángel Correa was hauled off for Fernando Torres.
Despite the change, Atletico continued to look lethargic in the opening minutes of the second half and Simeone decided to make another attacking substitution in the 54th minute with full back Juan Fran coming off for Vitolo.
Real still looked the better team and came close to scoring their second goal in the 64th minute. The impressive Januzaj collected the ball on the edge of the box and swivelled past a number of challenges before he curled a shot to the right of Oblak but the effort lacked power and it was a comfortable save for the keeper.
Moments later, Vrsaljko was inches away from finding Atletico's equaliser but his header from six yards out bounced just wide of Rulli's right-hand post.
As the game entered its final 20 minutes, the visitors started to push further upfield in search of an equaliser but were still struggling to carve out opportunities and were instead getting caught on the counter.
Willian Jose should probably have scored his second of the game in the 73rd minute when he was sent through on goal by Januzaj but the Brazilian dragged his shot wide. Juanmi was the next Sociedad player to be sent through by Januzaj in the 79th minute but his touch was too heavy and allowed Godin to get back and make the tackle.
La Real finally doubled their advantage with their next counter attack just moments later. This time, it was an excellent flick from Willian Jose which sent Juanmi through on goal and the Spaniard made no mistake, chipping a sumptuous effort over Oblak and into the empty goal.
Juanmi wasn't finished there and confounded Atletico's misery seconds from time when he planted De La Bella's excellent cross past Oblak with a looping header from eight yards out.