Algerian international Gouiri had impressed in his first two games since joining Marseille from Rennes late in the January transfer window, but he had not scored for his new club until Saturday's match at the Velodrome.

He opened his account to give Roberto De Zerbi's team a single-goal lead at the interval, before Mason Greenwood made it 2-0 from a penalty five minutes into the second half.

It was Greenwood's 14th Ligue 1 goal this season, a tally bettered only by Ousmane Dembele of leaders Paris Saint-Germain, who has 16.

Amir Murillo made it 3-0 and Gouiri got his second of the afternoon to make it four for the hosts, with Adrien Rabiot adding a fifth as he scored for the third game running.

Lucas Stassin pulled one back for Saint-Etienne, who remain in the bottom three and in real danger of an immediate return to Ligue 2.

Marseille are seven points behind PSG before the leaders and reigning champions play at Toulouse later on Saturday.

OM are also six points better off than their closest pursuers Monaco, who showed no mercy for struggling Nantes as they claimed a huge win at the Stade Louis II.

Biereth scored a hat-trick in a second consecutive home Ligue 1 game, the striker leading Monaco to a win which boosts morale following their 1-0 home loss to Benfica in the first leg of their Champions League play-off tie in midweek.

Biereth, a January signing from Sturm Graz of Austria, also netted three times in a 4-2 home win over Auxerre two weeks ago.

Matthis Abline had given Nantes an early lead in the principality, but former Arsenal youngster Biereth equalised and Japanese international Takumi Minamino put the hosts ahead in first-half stoppage time.

Eliesse Ben Seghir made it 3-1 before Biereth netted twice more, including from a penalty, to complete his hat-trick.

Two late goals from teenage Nigerian substitute George Ilenikhena then finished off the scoring, as Monaco warmed up for the return leg against Benfica coming up on Tuesday.