PSG was always the first power in the French League recently and they usually had perfect performances there but PSG is going to play against stronger teams too and it seems Marseille is now a much better team compared to the last season maybe because of having plays like Greenwood in this team. Marseille is definitely a good team in the French League but still, I don't think if Marseille can even beat a team like PSG with the good teamwork they have during this season thanks to Enrique. However, there is still enough time for both team because they start this match.
Marseille may have a very different performance in attack after having Greenwood but the defense is still the same as last season. Marseille could compete with PSG, but to get the league 1 title it seems very difficult. Whatever happens, PSG quality is much higher in terms of defense, it is very different and Marseille only has a perfect attack line. Unless the Marseille coach is able to provide a consistent strategy to continue to get points.
BTW, it seems that Greenwood will be a player who will continue to be discussed here if he has a good career and can score more. The former Man United player seems very comfortable playing with Marseille and does not need long to adapt.
You are right, Marseille weakness at the moment is their defense line which is not really solid and able to withstand various attacks when facing other strong team in Ligue 1, their opportunity is to take advantage of the upcoming transfer window to be able to improve their defense line.
For Greenwood in the three matches he has played with Marseille, he looks very good and as new striker it is very satisfying because he has been able to provide 5 goals at the start of his first season, this is development that really helps Marseille to be able to perform better considering that last season they could only finish in 8th place.
To be honest, fighting for the championship title is not easy, maybe there will be an opportunity for Marseille but if they can't take advantage of everything well then the opportunity is still very small to be realized.
I think if Greenwood performs well here and really brings Marseille towards better change then there will be interest for other teams to have him, it is even possible that PSG will also be interested in being able to have Greenwood in the future.