Darwin Machis and Jorge Molina scored in the second half to cancel out Lionel Messi's early opener as the Blaugrana remain third, behind leaders Atletico Madrid and Real Madrid. The win was Granada's first-ever at the Camp Nou.
Barcelona were in control until the hour mark and looked to be cruising towards another victory, but defensive lapses allowed Il Grana to claw their way back into the match, with Ronald Koeman getting sent off for an altercation with the referee.
Barcelona remain in third place with 71 points, tied with holders Real Madrid, who're ahead on goal difference, and two off Atletico Madrid, whom they play next weekend.
On that note, here are the player ratings for Barcelona:
Marc-Andre ter Stegen - 6/10
It was all going smoothly for the German till Granada opened Barcelona up at the back and scored twice. There was nothing Marc-Andre ter Stegen could've done about either of those strikes.
Oscar Mingueza - 6.5/10
He was good on the ball and had little to do defensively, although Suarez's pass for the equalizer went right through him. Oscar Mingueza was taken off soon thereafter.
Gerard Pique - 6/10
Gerard Pique's decline was very evident on the night. The veteran Barcelona defender left acres of space at the back while trying to throw his weight around in attack and was also beaten in the air by Molina for Granada's winner.
Samuel Umtiti - 4/10
It could be due to his lack of game time this season, or perhaps because he's still not at full strength. Either way, Samuel Umtiti was an unmitigated disaster on the night. If his terrible first-half backpass was a sign of things to come, his positioning for the second Granada goal was simply shocking.
Sergio Busquets - 6/10
Sergio Busquets looked shaky in possession in the first half but gained his composure gradually. The midfielder also laid a nice throughball for Roberto in the second half.
Sergi Roberto - 7/10
Sergi Roberto was a huge threat on the ball and made a couple of decent passes in attacking areas. He also had the chance to go for goal himself but squandered the opportunity by blazing over the bar.
Jordi Alba - 5/10
After some impressive displays, Jordi Alba was brought back to earth. He struggled to impose himself in the Barcelona attack and couldn't lay a single key pass.
Frenkie de Jong - 7/10
Frenkie de Jong constantly asked questions of Granada's defence by taking up good positions and also created space for his teammates to come into. The Dutchman made a game-high six key passes on the night as well.
Ilaix Moriba - 6/10
The Barcelona youngster got the ball forward by charging out of his line when in possession but lacked a good final ball. He made four recoveries, though.
Lionel Messi - 8/10
Once again, everything good coming from Barcelona flowed through Lionel Messi, who opened the scoring with a fine strike. He's on 26 league goals for the season now, closing in on yet another Pichichi trophy.
Antoine Griezmann - 6.5/10
Antoine Griezmann started the match brightly and got a shot away that flew narrowly wide of the post, but he faded in the second half.
Ratings of Barcelona substitutes
Ousmane Dembele - 6/10
Ousmane Dembele tried to make things happen by running at the Granada defence, but nothing significant came out of that.
Pedri - 6/10
Pedri made a few passes and looked to get involved from the moment he came on for Barcelona.
Francisco Trincao - N/A
It was too little, too late for the Barcelona youngster on the night.