Barcelona moved top of La Liga by a point but left disappointed after an end-to-end clash with Real Sociedad in San Sebastian.
A strange penalty, given after Sergio Busquets was said to have fouled Diego Llorente, saw the Basques break the deadlock.
Mikel Oyarzabal sent Marc-Andre ter Stegen the wrong way from the spot.
However Antoine Griezmann levelled for Barcelona, dinking the ball home neatly after being played in on goal.
He did not celebrate against his former side, out of respect.
“I will never celebrate here, I have a lot of respect to those who gave me everything,” explained the French forward.
Barcelona took the lead when Busquets played in Lionel Messi, who squared for Luis Suarez to convert.
However the Catalans, who had Jordi Alba and Nelson Semedo back from injury, could not find a third and the hosts equalised.
Alexander Isak fired home after Ter Stegen spilled Nacho Monreal’s effort to level.
Real Madrid can now move top by two points with a win at Mestalla on Sunday when they face Valencia, ahead of Wednesday’s Clasico.