Struggling Marseille clung on for a barely-deserved point, denying Brest a first win of the Ligue 1 season.
Romain Poyet gave the visitors an early lead, which was cancelled out in the 20th minute by Andre Ayew.
Brest had the best of the chances in the remainder of the game as Paul Baysse twice went close and home keeper Steve Mandanda - who was culpable for the goal - redeemed himself with two good saves, but OM survived.
A point is barely good enough for Didier Deschamps` men, though, who remain in the bottom half of the table having started the season looking to go one better than last year`s second-place finish.
Brest's opener came when home defender Souleymane Diawara lost possession in his own half and Poyet beat two men and fired in a low left-footed drive which squirmed beneath Mandanda and found the net.
It was almost two in the seventh minute when Nolan Roux's free-kick found Santiago Gentiletti, who scooped the ball inches over the bar.
And Ayew then levelled the scores, bundling home from close range after good work by Mathieu Valbuena and Loic Remy to create the opportunity.
Baysse could have restored Brest's lead on the half-hour when he headed Benoit Lesoimier's corner just wide.
And the same pair almost linked up once more in the second half, Lesoimier this time sending in a free-kick which Baysse lunged at but was just unable to reach.
Roux threatened in the 75th minute and drew a sharp diving save from Mandanda, whose opposite number Steeve Elana responded in kind to deny Remy.
There was a late scare for the hosts as Mario Licka delivered a free-kick which was repelled by the fists of Mandanda to condemn Brest to their seventh draw in the first nine games of the season.
