Tuchel named Neymar in his squad for their last-16 first-leg tie in Germany despite the world’s most expensive player missing the French club’s last four games through injury.
The return of Neymar from a rib injury in time for Tuesday's Champions League last 16 clash at Borussia Dortmund "changes almost everything... and brings a lot of confidence" to his Paris Saint-Germain team-mates, coach Thomas Tuchel said.
Tuchel named the Brazilian superstar in his squad for their last-16 first-leg tie in Germany despite the world's most expensive player missing the French club's last four games through injury.
He has been struggling with a rib problem but should be fit to play at Signal Iduna Park.
"He's fine, he's going to train, and will play if nothing happens to him," said Tuchel in Monday's press conference.
"He has the quality, the confidence and the ability to do decisive things. His presence changes everything - it gives me and his team-mates a lot of confidence.
"If he's missing, he's missing - but we don't have another player of that quality."Neymar missed last season's surprise last-16 loss to Manchester United with a foot injury, while he also sat out the second leg of the defeat at the same stage of the competition by Real Madrid in 2018.
He was rested, along with France forward Kylian Mbappe, for Saturday's remarkable 4-4 draw at Amiens in Ligue 1.
PSG are yet to reach the Champions League semi-finals since being bought by their Qatari owners nine years ago, with their run to the last four in 1994-95 still the closest they have come to lifting the European Cup.
Tuchel is under extra pressure to deliver as PSG have exited at the last 16 stage in Europe for the last three seasons.
"It's clear that if you lose three times in a row in the last 16, the situation is not the same the fourth time," admitted Tuchel.
"After the defeat (to Manchester United last season), we were sad, I was mentally almost dead, but that's sport.
"I said to the players (at the time): 'It might be a bit harder next year, but that's what we play in the Champions League for'.
"Sometimes you lose, you have to accept it and use the defeats to grow." Having coached Dortmund for two seasons before his dismissal in 2017, Tuchel knows to expect a passionate atmosphere.
"It's difficult to control your emotions in this stadium and I'm not sure it's possible for the 90 minutes," said PSG's German coach.
"It's necessary to remain calm, attentive and intelligent.
"Dortmund are very strong when they press and when they counter-attack."The hosts are missing Germany forwards Marco Reus and Julian Brandt, but Dortmund have a deadly teenage duo in striker Erling Braut Haaland and England winger Jadon Sancho, both just 19.
Haaland has scored a phenomenal nine goals in his six games for Dortmund.
"Their forwards' statistics are incredible," said Tuchel.
"We will have to block their counter-attacks before they start.
"It's going to be a challenge."