Goals from David Alaba and Lucas Vazquez saw Real Madrid secure a 2-1 victory at Barcelona to increase the pressure on Ronald Koeman.
Alaba registered his first goal since joining Real over the summer when he fired past Marc-Andre Ter Stegen just after the half-hour mark.
Vazquez doubled the advantage for Carlo Ancelotti's men in the third minute of stoppage time with a close-range finish, before substitute Sergio Aguero opened his Barca account by pulling a goal back with almost the last kick of the contest.
It made it three defeats from three Clasicos as Barca boss for Koeman, whose side have a LaLiga record this term showing 15 points after eight matches.
Following the game, footage posted on social media appeared to show Koeman's car being surrounded by fans as he drove away from the Nou Camp.
In response Barcelona posted a statement on their official Twitter account which read: "Barcelona publicly condemn the violent and disdainful acts that our manager experienced when leaving the Nou Camp.
"The club will take security and disciplinary measures so that such unfortunate events do not happen again."