Barcelona's 100 percent start to La Liga season was brought to a stunning end as Celta Vigo moved top of the table with a stunning 4-1 victory on Wednesday.
The side formerly managed by Barca boss Luis Enrique were deservedly given a 2-0 half-time lead by excellent finishes from Nolito and former Liverpool striker Iago Aspas.
Barca's first league defeat since February was sealed when Aspas struck again on the counter-attack early in the second period.
Neymar pulled a goal back for the visitors, but Celta rightly had the final word as John Guidetti rounded off a famous win with the Galicians' fourth nine minutes from time.
It is the third time Barca have conceded four goals in just nine games this season having been thrashed 4-0 by Athletic Bilbao in the Spanish Super Cup and beaten Sevilla 5-4 in the UEFA Super Cup.