Joao Pedro scored a sensational sixth Europa League goal with two minutes to go as Albion reached the knockout stages on another unforgettable night.
The Brazilian’s brilliant finish into the roof of the net brought Albion belated reward for a patient display and came just when it looked as if a resilient Marseille had done enough for the point which would have secured them top spot.
And if anything personified Albion’s patience on the night it was the way they probed patiently for the opening that brought the goal although the identity of both scorer and creator – Pascal Gross – were not much of a surprise.
When Joao’s shot ripped into the net Albion had completed a remarkable turnaround in their first season in Europe. At half-time in Marseille in early October they were 2-0 down having lost their first match. Since coming back to draw 2-2 at Stade Veledrome they have won all four games.
Come March they will be in the last 16 and will be a team to avoid when the knockout stages get underway.
Five Albion changes from the 1-1 draw against Burnley saw Jack Hinshelwood slot in at right-back, the position Roberto De Zerbi believes is his best.
Lewis Dunk had urged Albion fans to bring the noise and they responded to create a brilliant atmosphere at kick-off, with the Marseille supporters adding to the colour of the spectacle.
Albion were first to threaten with a curling shot by Simon Adingra straight at Pau Lopez and he was involved again when he found Hinshelwood out wide. A fizzed cross was met by Joao but his shot was off target as the hosts made the early running.
Marseille, of course, needed a draw to top the group and that task was nearly made easier on 15 minutes when Jonathan Clauss’s shot deflected off Igor and looped over Steele but came back off the bar before being Jan Paul van Hecke cleared. At the other end Joao held the ball up for Kaoru Mitoma but Lopez got behind his low drive before Joao’s volley was blocked. Albion would have been pleased with their attacking tempo in the first quarter of the game.
Joao had another chance on 40 minutes. Gross was the creator with a clever inside pass to the Brazilian who cut inside a defender to make space but his left-foot shot was straight at Lopez.
Billy Gilmour came nicely onto Adingra’s pass on the edge of the box three minutes after the break but again his shot was too close to Lopez and Adingra should have done better than scoop his shot over after a typically direct cross-field run by Mitoma to set up the opportunity.
For all their pressure Albion needed luck again on the hour when Amine Harit shot through a crowded box and struck Steele’s right-hand post before van Hecke athletically scooped the loose ball away – another warning for the Seagulls.
Evan Ferguson, James Milner and Adam Lallana came on but it appeared to be turning into a frustrating night, not least when Ferguson’s shot from the edge of the box was fingertipped over by Lopez, but the referee awarded a goal kick.
But Albion stirred themselves for one last push and two minutes from time the breakthrough came. The move started with van Hecke finding Lallana in a pocket of space and then Gross picking out Joao with the perfect pass. There was still a lot for him to do, but he worked half a yard of space ten yards out and smashed a left-foot shot into the top corner. Cue delirium and when the smoke from several flares cleared Albion could see a clear path into the knockout stages.
Albion: Steele, Hinshelwood (Milner), Dunk, van Hecke, Igor, Gilmour (Baleba 90), Gross, Adingra (Ferguson 64), Mitoma, Buonanotte (Lallana), Joao (Baleba 90).
Subs not used: Verbruggen, McGill, Dahoud, Hinchy, Chouchane, Kavanagh, Duffus.
Referee: Jose Sanchez Martinez (Spain)
Attendance: 30,214