Neymar has struggled with a groin issue in recent weeks and was a doubt for the decisive Champions League clash with Red Star Belgrade, before starring in the victory that took PSG through to face Manchester United in the next round.
The world's most expensive player then declared himself "back to 100 per cent" in an interview with the club's official website this week.
But head coach Tuchel is not prepared to take a risk with a key man and has instead allowed Neymar to travel home to Brazil, missing the side's final match of 2018 against Nantes on Saturday.
"Neymar has gone to Brazil with my permission," Tuchel told a pre-match news conference.
"He played injured against Red Star. It was a risk.
"We are happy that things have not got any worse after the game. Ney always wants to play, but this is not the time to take risks."
Neymar suffered a fractured foot in February and was absent as PSG crashed out of the Champions League against Real Madrid the following month.
He said of his return to fitness:"Coming back and getting to play alongside and be with your team-mates is always great.
"It was a pretty sad situation, with my injury and then our defeat at the World Cup, but you need to draw inspiration from such episodes and come back to focus on new objectives.
"I think it was a tough start to the season, but it was very important and the work we did was excellent. Now I feel back to 100 per cent.
"It was tough to adapt to my return to competition and playing matches after my injury and the operation. But now I feel really good."