PSG won five of the past six domestic titles and have already opened a sizeable gap after eight matches of the new season.
But the domestic dominance is yet to translate into European success, despite chairman Nasser Al-Khelaifi's heavy investment in a succession of marquee signings.
Tuchel has been tasked with improving on a series of premature exits and, while World Cup winner Deschamps admires the ex-Borussia Dortmund boss, he harbours concerns over the competitive preparation provided in Ligue 1.
"[Tuchel] has a high level of social skills, works meticulously, has authority and at the same time has a certain closeness to the players," Deschamps told Bild.
"[But] there is a lot going on Paris. He's not a magician.
"They play in a league where they win most of the games even with the handbrake on and then suddenly find themselves in the Champions League again, against an opponent where the quality and aggression is completely different.
"The squad is not used to that."
They head into that match following a comfortable 3-0 victory at Nice that saw them become the second side in Ligue 1 history to win their opening eight games.