Barcelona's Neymar reacts after missing a scoring opportunity during Saturday's La Liga match against Granada at Nuevo Los Carmenes stadium in Granada. Pepe Marin / Reuters

Barcelona's nightmare week hit a new low when it followed up its Champions League exit with a shock 1-0 defeat at Granada on Saturday that left its bid for a fifth La Liga title in six years in serious jeopardy.

After Atletico Madrid dumped it out of Europe's elite club competition on Wednesday, Barca sought a morale-boosting domestic win that would have put it two points clear at the top ahead of Atletico, which plays at Getafe on Sunday.

However, the Spanish champion again looked lethargic and short on ideas against a club with a fraction of its resources and surrendered second place to archrival Real Madrid, which thumped struggling Almeria 4-0 at the Bernabeu to draw level on 79 points with Atletico.

Atletico can stretch its advantage at the top to three points with a win at Getafe. It plays at Barca in its final match of the season and will already be assured of its first Spanish league title since 1996, when current coach Diego Simeone was in the side, if it wins its next five matches.

"The league is not in our own hands anymore," Barca coach Gerardo Martino said.

"There is no reason to criticize the team, they gave it everything they had," said the Argentine, who is in his first season in charge at the Nou Camp and now needs to lift his players for Wednesday's King's Cup final against Real.

"The ball did not want to go in and that is that. We just weren't up to scratch in taking our chances."

Barca fell behind at Granada's Nuevo Los Carmenes stadium when Alex Song lost possession in midfield in the 16th minute and Yacine Brahimi raced clear and fired past goalkeeper Jose Manuel Pinto.

It dominated the rest of the match but Granada, which is fighting to avoid relegation, held firm against waves of attacks and the Catalan giant's second consecutive defeat will do little to dispel the impression of a club in crisis.

It had almost 90 percent possession but not even four-time World Player of the Year Lionel Messi, who turned in another subdued performance, or Brazil forward Neymar could unlock a stubborn home defense.

Neymar had several clear chances, while Messi drew a fine save from Granada goalkeeper Orestis Karnezis with a free kick just after the hour.

Sergio Busquets almost scored when the ball fell to him at the resulting corner but his close-range effort was straight at the keeper.

"This is a step backwards," Barca playmaker Andres Iniesta, who was captaining the side in place of the rested Xavi, said in an interview with Spanish television broadcaster Canal Plus.

"Sometimes it is hard to find an explanation when you lose but we just couldn't get the goal," said the Spain international.

"Teams like Granada who are playing for their La Liga survival live and die on chances like the one they scored but that was too much punishment for us."