Gomis treble as Marseille return to form with Evra
Marseille were coming off defeats against leaders Monaco and Lyon as they moved into the top five thanks to an irresistible attacking showing at the Stade Velodrome.
Handing a debut to former Manchester United stalwart Patrice Evra, the former European champions were more solid at the back than they have been for much of an inconsistent campaign.
At the other end, meanwhile, Gomis, on loan from English Premier League side Swansea, showed his mettle with goals which made him the first man to score a hattrick both for and against OM.
The 31-year-old former Saint Etienne and Lyon forward took advantage of two headed passes from former Newcastle misfit Remy Cabella to score the opener on four minutes and his second on 19 minutes.
Rolando made it 3-0 on 38 minutes before Ryad Boudebouz pulled one back four minutes after the restart.
But Gomis notched his third with 13 minutes remaining and a penalty from another Newcastle flop, Florian Thauvin, underlined the dominance of Marseille as they recorded their biggest win since being taken over by US businessman Frank McCourt.
"We really wanted to get back to winning ways and have the team show what it is made of," said Marseille coach Rudi Garcia, who nonetheless ticked off his side for a poor showing in the opening 20 minutes of the second half.
Evra put in an impressive 72-minute shift after his arrival from Juventus this week as Marseille recorded a win which lifted them provisionally into fifth place, five points adrift of leaders Monaco.
Garcia praised Evra for his showing and "showing his playing quality while also being someone who exudes calm and transfers it to his teammates."
The Monegasques take on third-placed Paris Saint-Germain, champions for the past four seasons, on Sunday.
Second-placed Nice, two points off Monaco, take on a Guingamp side who could leapfrog Marseille in the event of victory on the Cote d'Azur.