Despite nine goals from Dika Mem and 13 saves from keeper Emil Neilsen, the visitors took a narrow win to spoil the party for the blaugranes who could otherwise have secured their 15th successive league title with a win.
Barcelona have dropped points in their domestic league campaign in previous seasons. But this is the first time since 13 April 13, 2018 that they lost a league match in the Liga Asobal. Back then Granollers were also the executioners as Barca lost 29-28.
Barça went 3-1 up early in the contest but the visitors fought back strongly to take a 6-3 lead after eight minutes and force Barcelona coach Carlos Ortega into a time out. Granollers then managed to stretch their advantage to 10-6 before Barça dragged themselves back into the contest thanks to the services of Dika Mem and Nielsen who made several stops to allow the the home side to lead 18-16 at the interval.
Barça started the second half well taking a four goal lead at 24-20. However, Granollers fought back to level things up at 29-29 with just five minutes remaining. In a frenetic final stretch with the Palau crowd willing them on, Barça were denied by visiting keeper Roberto Rodríguez making a string of important saves to lead the visitors to a sensational win.
Barcelona now have three more league games to play before facing Szeged over two legs in the Champions League at the end of April and the beginning of May. The overall winner will secure a place in the Final 4. Barcelona are the defending Champions League winners.
Barca lead the Spanish domestic league by 10 points to second-placed Granollers, with seven games remaining in the Liga Asobal.