Lucho González's penalty earned FC Porto a share of the spoils and restricted UEFA Champions League Group A leaders Olympique de Marseille to a draw that nonetheless kept the French club two points clear of the visitors.
Both coaches admitted beforehand that a draw would be a favourable result, but the outcome owed more to accident than design. Marseille battled valiantly to establish the lead midway through the second half thanks to Mamadou Niang, only for González to restore parity from the spot with eleven minutes remaining.
The two teams came out eager to impress, yet it was the trickery of Ricardo Quaresma that gave Porto early supremacy. He set up Paulo Assunção for a long-range attempt and although the Brazilian blasted over, Jesualdo Ferreira's side did not have to wait long for another opening. This time, Bosingwa picked out Raul Meireles through the middle and the Portuguese international cracked an effort against Steve Mandanda's right-hand post from 20 metres.
For Marseille, Senegal forward Niang showed plenty of verve but was let down by some clumsy touches and the hosts were soon on the back foot again, Laurent Bonnart timing a sliding tackle to perfection to deny Lisandro López. Remarkably Meireles kept up the Porto pressure by hitting the same post for the second time, setting himself up for a half-volley that Mandanda touched on to the woodwork.
Erik Gerets's surprise central-defensive pairing of Jacques Faty and Ronald Zubar were doing their best to cope, but they could have done with more support from midfield. Instead, Marseille yielded possession far too easily in their build-up play, leaving them in need of a set-piece to create their first chance after 34 minutes. Boudewijn Zenden attempted the spectacular from a right-wing free-kick and Helton punched clear.
Clearly feeling his team ought to press home their advantage, Ferreira replaced Mariano González with striker Hélder Postiga after the break. It was fellow forward López who produced the first opening of the half, though, forcing Mandanda to palm over his header from the penalty spot, but Postiga soon announced his arrival by breaking down the left and drilling the ball into the side-netting.
Gerets responded by sending on Salim Arrache for Zenden, and his charges almost immediately upped their tempo, with Niang striding confidently into the area and stinging Helton's hands with a fierce low drive. There was a sudden composure to Marseille's play and a goal duly followed in the 69th minute. Djibril Cissé brought the ball under control out on the right and blasted it across goal from the touchline, enabling Niang to bundle in at point-blank range.
The Vélodrome faithful erupted with joy, yet their elation evaporated ten minutes later when Mandanda was adjudged to have fouled López in the box. González converted from the spot, as he had done against Liverpool FC on Matchday 1, and for all Marseille's late bustle they were unable to restore their advantage. The two rivals will nonetheless have another chance to assert supremacy at the Estádio do Dragão on 6 November.