Porto can take a giant stride towards the Champions League knockout stages when they travel to the Orange Velodrome to take on Marseille in Wednesday's showdown.
In contrast, the hosts are rock bottom of Group C and their European venture looks set to come to an end as soon as it began following a dismal start.
Match preview
Marseille manager Andre Villas-Boas had some choice words for his team after their third-straight Champions League defeat earlier this month, and given how Les Olympiens have played so far, the Portuguese's scathing assessment was not all that surprising.
The Ligue 1 outfit have not even registered a goal yet alone a point in Europe's elite competition, and Marseille supporters have very little to feel optimistic about as their side's first outing in the Champions League since the 2013-14 season seems destined to come to a premature end.
Les Olympiens suffered a cruel defeat to Olympiacos and a deserved loss to Manchester City before facing Porto in gameweek three, and the Portuguese champions comfortably swept aside Marseille 3-0 in that encounter, with Moussa Marega, Sergio Oliveira and Luis Diaz all finding the back of the net earlier this month.
Marseille did manage to overcome Strasbourg 1-0 before the international break, but their proposed Ligue 1 encounter with Nice was called off due to coronavirus cases in the Aiglons camp, which has allowed Villas-Boas plenty of time to ponder how he can salvage Marseille's Champions League campaign ahead of the festive period.
Anything but a win and Marseille will kiss their already-slim hopes of making the knockout stages goodbye, although a third-placed finish is still within reach as Olympiacos sit just three points above Les Olympiens, whom they will take on at the beginning of December.
Meanwhile, Porto look set for yet another stint in the knockout stages and their top-two finish will be almost guaranteed if they beat Marseille and Olympiacos lose to Manchester City in midweek.
Sergio Conceicao's team have plenty of experience on the European stage and are unlikely to throw this away now, and the Portuguese champions go into this game in great form having prevailed in five of their last six matches in all competitions.
Despite losing to Man City in their inaugural Champions League fixture of the campaign - a defeat which saw their abysmal record on English soil continue - Porto eased to victory over Marseille and also comfortably swept aside Olympiacos 2-0 in gameweek two.
Even if Porto win this week and Olympiacos lose, it is still possible for the Greek powerhouses to pip Porto to second spot, but Conceicao's men would need to have a monumental collapse for that to happen.
Since overcoming Marseille 3-0 earlier this month, Porto registered a 3-1 league victory against Portimonense, and the champions also overcame third division side Fabril Barreiro 2-0 in the Taca de Portugal at the weekend.
Marseille Champions League form: LLL
Marseille form (all competitions): WLWLLW
Porto Champions League form: LWW
Porto form (all competitions): WWLWWW
Team News
The good news for Villas-Boas is that the Marseille manager is spoilt for choice with regards to team selection, with no injury or suspension concerns whatsoever for the clash with Porto.
Marseille certainly have concerns on the attacking front, though, with Dario Benedetto still without a goal 11 games into the season, and the Argentine's place is under threat by Valere Germain here.
Hiroki Sakai and Alvaro Gonzalez missed out the win over Strasbourg through suspension but both are set to start here, while Morgan Sanson's winner against Les Coureurs has put him in contention for a recall to the midfield.
Meanwhile, Porto have a couple of defensive concerns to deal with as Pepe and Ivan Marcano are set to miss out through injury, while goalkeeper Mouhamed Mbaye is recovering from cruciate ligament surgery.
Liverpool loanee Marko Grujic is also unavailable after suffering a concussion, but the 24-year-old would have struggled to force his way into the midfield over the likes of Otavio, Mateus Uribe and Oliveira.
Marseille possible starting lineup:
Mandanda; Sakai, Gonzalez, Caleta-Car, Amavi; Kamara, Rongier, Sanson; Payet; Thauvin, Germain
Porto possible starting lineup:
Marchesin; Manafa, Mbemba, Sarr, Sanusi; Oliveira, Uribe, Otavio; Corona, Marega, Diaz
We say: Marseille 1-2 Porto
There are no two ways about it - Marseille simply have to win if they are to have any hope at all of keeping their knockout dreams alive. However, Villas-Boas's men are clearly up against it and have already been beaten convincingly by Porto once this term, and while we expect the hosts to finally hit the back of the net in Europe, Conceicao's side should take another step towards the next stage with a narrow victory at the Orange Velodrome.
