The Dutchman is the Reds' second highest scorer this season with 16 but has been struggling with an ankle problem in recent weeks, which has made his game time inconsistent with forwards such as Luis Diaz and Diogo Jota getting more minutes on the pitch.
Slot was already set to be without four players for the huge game with Joe Gomez, Conor Bradley and Tyler Morton and now without Gakpo PSG will be full of confidence as Liverpool travel to the Parc de Princes this week.
The likes of Ibrahima Konate, Andy Robertson and Harvey Elliott all one yellow card away from picking up a one-game suspension and if Gakpo’s injury is serious they may miss several key stars ahead of the second leg at Anfield in a few weeks' time.
Head coach Arne Slot is due to speak to the media later today and should give an update on Gakpo who if injured is unlikely to start against the Ligue 1 side who have looked very impressive this season.