Messi has been at the club for more than a month but has yet to make his full debut. The Argentine, 34, was expected to do so last weekend but was rested against Clermont after returning from international duty with Argentina.
However, PSG manager Mauricio Pochettino is almost certain to unleash the six-time Ballon d'Or winner from the start at the Jan Breydel Stadium in Bruges on Wednesday.
And if Kylian Mbappe and Neymar also start, it will be the first instance of the superstar attacking trio together on the pitch for the Parisians.
However, Pochettino said he had not decided yet whether Mbappe, Neymar and Messi would all play at the Jan Breydel stadium, explaining he would make a late decision.
Pochettino said his team has some other challenges to overcome.
"We're not a team yet. We are a club that has recruited many players this summer. There are some big names but we have to turn into a team," Pochettino said.
"We are a group of players who need to achieve results. There's a feeling that we're [PSG and Chelsea] the two teams to beat but Chelsea are the holders so they're the team to beat especially after strengthening their squad."