A goalkeeping gaffe by Neto condemned Barcelona to a 1-1 draw at 10-man Alaves on Saturday as Ronald Koeman's team dropped points for a fourth straight round in the Spanish league.
Neto gifted Alaves its goal in the 31st minute when he let Luis Rioja poke the ball from his feet and roll it home.
Antoine Griezmann got his first goal of the season as Barcelona equalized in the 63rd after the hosts lost Jota Peleteiro to a second booking.
Barcelona surged forward looking for a winner, but Alaves 'keeper Fernando Pacheco kept out shots from Lionel Messi, Ansu Fati and Miralem Pjanic to salvage the point.
Barcelona's latest slip in the domestic competition comes three days after it dominated Juventus in a 2-0 win in Turin in the Champions League.
After winning the first two games of the league season, Barcelona has drawn two and lost two.
Barcelona is eight points behind leader Real Madrid with a game in hand.
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