Marseille were looking to consolidate their place in the automatic UEFA Champions League spots, in the third-most played fixture in the history of Ligue 1 against Saint-Etienne.
Unsurprisingly, given the two teams were at opposite ends of the table Marseille started on top, and they thought they had taken the lead early on when Leonardo Balerdi found the back of the net with a header from a corner.
However, after a VAR review, the goal was chalked off due to a foul on Gautier Larsonneur in the build-up to the goal.
Saint-Etienne did not heed the warning from that lucky escape and found themselves behind shortly after when new signing Amine Gouiri got his first goal for the club with a wonder strike from the edge of the area that flew into the top corner to make it 1-0.
This left a massive task for the visitors, who hadn’t won on the road in the league all season. Their best chance in the first half fell to Benjamin Bouchouari, who tested Geronimo Rulli with a fierce effort that the Argentinian was equal to, to leave the scoreline at 1-0 at the break.
After a quiet end to the opening 45 minutes the second half started very dramatically when Mickael Nade was shown to handle the ball in the area by a VAR review.
After a penalty was awarded, Mason Greenwood stepped up and he made no mistake, scoring his 15th goal of the season.
Les Verts were all over the place after going two behind and deservedly conceded again when poor defending allowed Quentin Merlin to fire an effort at Larsonneur, who palmed it right at Michael Murillo for an easy tap-in.
It then went from bad to worse for the visitors who then conceded two goals in two minutes.
This time a simple Pierre-Emile Hojbjerg ball through the middle put Gouiri in on goal, who made no mistake in securing a brace with a dinked finish.
Marseille were not done there however, and more woeful defending saw an unmarked Adrien Rabiot at the back stick have a simple tap-in from an Amar Dedic cross.
Saint-Étienne finally gave their travelling fans something to cheer about 79 minutes in when a well-worked move was finished off by Lucas Stassin for a consolation goal.
That was the last time either side found the net, with the game being comfortably seen out by the hosts to secure a 5-1 victory that takes them to seven points behind leaders PSG, having played a game more.
Flashscore Man of the Match: Amine Gouiri (Marseille)