The hosts were not finished though, and added another through Messi in stoppage time for 3-0.
Read how it all unfolded in Sports Mole's minute-by-minute live commentary of the action below.
BARCA: Ter Stegen; Semedo, Pique, Umtiti, Alba; Rakitic, Busquets, Roberto; Messi, Suarez, Dembele
ALAVES: Pacheco; Martin, Laguardia, Maripan, Duarte; Manu, Wakaso, Torres; Jony, Sobrino, Ibai Gomez
👥 Barça subs: Cillessen, Coutinho, Arthur, Rafinha, Malcom, Lenglet and Vidal— FC Barcelona (@FCBarcelona) August 18, 2018