Bournemouth were denied a first Premier League win under Marco Rose as a calamitous mistake by goalkeeper Djordje Petrovic allowed Brentford to claim a 2-2 draw at the Vitality Stadium.
The Cherries had been on course for victory at the fourth time of asking under the German coach when goals from Justin Kluivert and Marcus Tavernier overturned Kevin Schade's opener.
But Schade lobbed his second of the afternoon into an unguarded net to maintain the Bees' unbeaten start, following a dreadful pass from Petrovic.
It was the fourth time in as many league matches since Rose's summer appointment that Bournemouth have dropped points from a winning position.
Brentford move on to six points from a possible 12 following a third consecutive draw, while Bournemouth have just three.
The Cherries were seeking a first Premier League win over Brentford in the ninth such meeting between the clubs, ahead of beginning their Europa League campaign at Real Sociedad on Thursday.