Sixteen-year-old Ansu Fati became Barcelona's youngest ever La Liga goalscorer but could not prevent his side stumbling to a surprise 2-2 draw with Osasuna at Estadio El Sadar, which left the champions with only four points after three games.
However, the match, there was a minute's silence held in memory of former manager Luis Enrique's daughter who died from bone cancer.
Roberto Torres smashed a volley past Barcelona goalkeeper Marc-Andre Ter Stegen seven minutes into the encounter before the-16-years and 298 days old came on as a substitute and scored his first professional goal after six minutes to equalise for the Spanish champions.
Another substitute Arthur Melo scored his first goal for Barcelona in 45 appearances with a curling effort to put the visitors ahead with less than 10 minutes to go, Osasuna were awarded a penalty when the ball struck Gerard Pique's arm and Torres grabbed his second from the spot.
Ernesto Valverde's side have started the campaign with one win, one defeat and one draw and Atletico Madrid could move five points clear of them tomorrow with a win at home to Eibar, while Osasuna unbeaten so far on their return to LaLiga.