Eric Garcia and Jules Kounde have been ruled out after Barcelona's victory over Sevilla, while Gerard Martin is also doubtful after experiencing foot discomfort.
De Jong has returned from injury and could provide a solution, despite his usual role in midfield. Flick is also looking at Alex Campos as he weighs up his defensive options ahead of the trip to Paris.
"Frenkie de Jong can play, and Alex Campos is also with us. I am certain everything will go well," Flick told reporters.
"Perhaps we are not going through the best moment, but we have to accept that."
Despite the injury concerns, Flick believes the match offers Barcelona an important opportunity to measure themselves against Europe's strongest opposition.
"I think tomorrow's game is a good test for us. I want our team to play with confidence, as a side that has won its last 11 matches does," he said.
Flick acknowledged the scale of the challenge, describing PSG as "the best team in the world over the last two years", but insisted his players should approach the contest with belief.
Barcelona face the European champions at the Parc des Princes on Tuesday, with Flick hoping his team can overcome their defensive problems and maintain their confidence in a demanding Champions League encounter.
Aden McCarthy netted his maiden goal in the UEFA Champions League but it was not enough for his team Sabah as they fell to a 2-1 home defeat against Borussia Dortmund in Baku.
Marc Guehi believes Manchester City can continue to develop under Enzo Maresca as they prepare to face AEK Athens in the UEFA Champions League on Tuesday.
Barcelona midfielder Pedri has jokingly warned his close friend Ferran Torres not to score when the Catalan side face Paris Saint-Germain in a major Champions League clash tonight at Parc des Princes.
Niko Kovac has challenged Borussia Dortmund to end their winless run and rediscover their scoring touch when they face Sabah FK in the Champions League on Tuesday.
