Didier Drogba's late strike earned Marseille a draw at Liverpool in their Uefa Cup fourth round first leg tie.
In a woeful first half Steve Marlet blazed wide of an open goal and Michael Owen fired straight at Fabien Barthez.
The game improved after the break and Baros opened the scoring when Abdoulyae Meite's attempted clearance cannoned off him after Steven Gerrard's run.
Marseille struck back through Drogba's well-taken finish, before Gerrard's low drive was saved by Barthez's legs.
Both sides started with an attacking intent, Marlet testing Chris Kirkland with a low drive after a minute and Owen and Baros running with pace at the visitors' backline.
Liverpool nearly found themselves a goal down when Kirkland, Stephane Henchoz and Drogba clashed on the edge of the Reds' box and Marlet planted the ball wide with the goal gaping.
But the game soon became bogged down in a midfield stalemate, with neither side threatening to break the deadlock.
55 mins: Baros' deflection puts Liverpool ahead
78 mins: Drogba's brilliant control and finish levels it
80 mins: Gerrard's low shot is saved by Barthez
Harry Kewell appeared off-colour and off the pace, but he did find Owen with a left-wing cross that the England man fired straight at Barthez.
But in truth it was a poor contest between two sides that appeared badly out of form and completely lacking in confidence.
Liverpool captain Gerrard attempted to get his side going, but his team-mates were simply not up to making the most of his driving runs and neat passes.
The second half started in much the same vain as the first, with both teams looking to steal a precious goal on the counter-attack.
And finally Gerrard's determination paid dividends. After Dietmar Hamann had wastefully headed his free-kick onto the roof of the net, Liverpool edged in front.
Another surging Gerrard run into the box ended with the ball running into Baros' path, and as Meite tried to hook the ball away, it ricocheted off Baros and into the net.
Liverpool seemed content to sit on their lead and kill the game off, and Marseille's lack of ambition in the final third made another goal look unlikely.
But the visitors did get on the scoresheet when Drogba produced a sublime piece of control and showed great strength to hold off Jamie Carragher and slam the ball past a helpless Kirkland.
Liverpool responded immediately when Gerrard burst through down the left, but his right-foot drive cannoned off the legs of Barthez and away to safety.
In the last minute Hyypia's header was cleared from danger before Barthez got down well to parry away Baros' drive.
Liverpool: Kirkland, Finnan (Biscan 89), Henchoz, Hyypia,
Carragher, Murphy (Heskey 82), Hamann, Gerrard, Kewell, Baros,
Subs Not Used: Diouf, Riise, Sinama Pongolle, Cheyrou, Dudek.
Marseille: Barthez, Beye, Hemdani, Meite, Perez (Ferreira 62),
N'Diaye, Flamini, Dos Santos, Batlles (Meriem 67), Marlet,
Subs Not Used: Mido, Johansen, Ecker, Celestini, Gavanon.
Referee: Yuri Baskakov (Russia).