Though they returned from the international break with a disappointing draw, Paris Saint-Germain's recent slip-ups see OM just six points off top spot with nine games remaining - and they have beaten this week's hosts in each of their last seven league meetings.
Match preview
After their crushing home loss in Le Classique last month, even Marseille's most ardent fans may have assumed the Ligue 1 title race was over, yet an opening still remains for the southern giants to secure a first championship triumph since 2010.
PSG's sclerotic form in 2023 means OM are still in range of the summit, and they sit third in the standings with 60 points from 29 games. Incidentally, only two teams have ever been outside the top two at this stage with such a tally (during the three-points-for-a-win era).
However, a 1-1 draw versus Montpellier last week continued Marseille's tepid home form, and they have now taken only 25 points from a possible 45 at the Velodrome this term - in addition to exiting the Coupe de France there against second-tier Annecy.
By comparison, their away record under Igor Tudor is comfortably the best in the French top flight, and ahead of Sunday's trip to Brittany they have dropped just nine points in 14 away matches.
Marseille have won each of their last eight away games in Ligue 1, and victory this weekend would see them equal their own national record of nine, set some 14 years ago.
Having also enjoyed a 3-1 win in January's reverse fixture, when they came from behind to maintain their long success streak against Lorient, they will surely expect to do the double over their Breton counterparts and apply more pressure to PSG.
All told, Lorient have won just two of their 15 home games against Marseille in Ligue 1, and none since April 2012, so precedent will be stacked against them on Easter Sunday.
Les Merlus also come into the game with only one point from their two most recent outings, having had a man sent off on both occasions; last week, Lille's Edon Zhegrova came off the bench to bag a brace and consign them to a 3-1 defeat at Stade Pierre-Mauroy.
Despite that defeat, Lorient's haul of 44 points so far represents their best-ever tally after 29 games of a Ligue 1 season, and a top-half finish is certainly within sight.
Following the debilitating departures of Terem Moffi and Dango Ouattara during the January window, coach Regis Le Bris has had less attacking potential to threaten opponents with, so his side have focused on staying compact and aiming to counter-attack.
Having recently penned a two-year contract extension until 2027, Le Bris will be keen to end a season which started so spectacularly - with eight wins from 10 - on a high, and taking the scalp of OM would undoubtedly aid him in that cause.
Lorient have won three of their last five home games in Ligue 1, after going winless through their previous five, so achieving such an upset is far from impossible.
Lorient Ligue 1 form:
W
L
D
W
D
L
Marseille Ligue 1 form:
W
L
W
D
W
D
Marseille form (all competitions):
L
L
W
D
W
D
Team News
Though still without Morocco star Azzedine Ounahi due to a toe injury, Marseille will welcome back Leonardo Balerdi from suspension on Sunday.
Midfielder Valentin Rongier has filled in as OM's third centre-back, but Balerdi should now join Samuel Gigot and Sead Kolasinac - who recently overcame a groin strain - in the vistors' defence.
Despite being criticised by Igor Tudor for his lack of application in training, Nuno Tavares has scored six Ligue 1 goals as a wing-back this season and starts on the left flank; 12-goal top scorer Alexis Sanchez features up front.
Lorient, meanwhile, have remained winless in eight games without Laurent Abergel, and the defensive midfielder is suspended this week following his dismissal during the loss to Lille. Back from injury, Bonke Innocent should replace him.
Even more responsibility therefore falls on Enzo Le Fee, and the 23-year-old local lad - who represented France at the Tokyo Olympics - has been directly involved in nine league goals this term. However, he has been absent from training with a thigh problem and may not be ready to start.
While Igor Silva serves the second match of his ban, Romain Faivre is back in contention and will compete for a place in midfield.
Lorient possible starting lineup:
Mannone; Yongwa, Meite, Talbi, Le Goff; Innocent; Faivre, Le Fee, Makengo, Cathline; Dieng
Marseille possible starting lineup:
Lopez; Gigot, Balerdi, Kolasinac; Clauss, Guendouzi, Veretout, Tavares; Under, Malinovskyi; Sanchez