At this time Lens is right below PSG in the standings while second in Ligue1 and yes PSG must be able to win the game this weekend so that the gap in points can continue to be created even though PSG can still be at the top of the standings if they lose this weekend's game. However, PSG must be able to try to win at home in this match besides having to get full points in the match because Lens is not far behind PSG in the standings.
That's true that Lens is the second team and they have fewer points than PSg but the fact is PSG is in a bad situation which is a good reason to say there is the possibility for them to lose even easier games than Lens, While Lens have too much hope for this game and they can have the chance to beat PSG and decrease the gap between themselves and PSG.