The world's most expensive player sat out Friday's Ligue 1 win at home to Saint-Etienne after returning from international duty.
But Tuchel said Neymar will be in his starting line-up for Tuesday's Champions League opener away to last season's beaten finalists.
Neymar has played in a number 10 role at times this season but Tuchel would not reveal whether the forward will feature in that position or from the left flank, while he is also keeping his plans for Angel Di Maria to himself.
"I will not tell, of course," Tuchel said at Monday's news conference. "What is sure is that he will play, but in which role, I will not tell!
"It's never a risk to trust Di Maria. In which role though, same as Neymar - I cannot tell you. It would make it very easy for Liverpool to prepare."
The showdown at Anfield presents a difficult test for a PSG side that has struggled in the business end in the tournament in recent years, failing to move further than the quarter-finals since 1995.
That has not deterred Liverpool manager Jurgen Klopp from believing PSG are among the favourites for the Champions League title but Tuchel is not about to get caught up in favourites talk, as he does not think it brings any positives for his team.
"We can talk about this for hours and hours, but it doesn't bring you one centimetre closer to the title," Tuchel added.
"It doesn't make sense to talk about things that happen next year. We like the challenge to play here and the challenge for our group.
"In my opinion, a challenge, a game like this can never come too early. This will bring out the best in us, get us used to this pressure, this kind of level. There is no problem with that. What we need tomorrow is the best performance we have.
"You can never be comfortable against Jurgen's teams, or at Anfield, but this kind of opponent, atmosphere, brings out the best in us. I believe we can be a very dangerous opponent tomorrow."
Paris Saint-Germain (@PSG_English) September 17, 2018
Tuchel also bristled at a suggestion PSG must concentrate on the Champions League as winning Ligue 1 should be a straightforward task.
"I disagree with you, it is not easy," he hit back at a journalist. "It's a point of view which does not help us in the club.
"If we judge ourselves only by the biggest goal you can have in European football, then the possibility for disappointment is very high. Why should we do this?"