Sevilla, under new boss Pablo Machin, were impressive and led after Sarabia received Luis Muriel’s pass and placed it past the goalkeeper early on – with a goal eventually awarded following a VAR review.
Barca equalised late in the first half when Lionel Messi’s free-kick hit the post and the back of goalkeeper Tomas Vaclik, and Pique turned home the rebound into an empty net.
Sevilla then hit the crossbar from Franco Vazquez’s looping header as both sides pushed for victory.
Dembele who sealed the game when he lashed a shot home from 20 yards via the underside of the crossbar in the 79th minute.
There was more action to come, with Ben Yedder’s miserable penalty, but Barca – who handed debuts to Clement Lenglet, Arthur and Arturo Vidal – win for the sixth time in nine years.