The German spoke a day after midfielder Julian Draxler told AFP that the "egos" of Neymar and the French champions' other star forwards did not always make it easy for the team.
Tuchel is under pressure to take PSG deep into the Champions League in the forthcoming season, while successfully defending their Ligue 1 title is almost a formality.
Tuchel was not forthcoming on the future of Neymar, saying he had "no news", after the Brazilian made it clear that he wants to return to Barcelona.
"For me, he's our player... it (his future) is a question between him and the club," was all Tuchel would say.
But he was forthright about what he wants from his star-studded squad, which earlier in the day was embellished by the arrival of Everton midfielder Idrissa Gueye.
With PSG playing Rennes in the domestic Trophee des Champions on Saturday in Shenzhen, Tuchel said: "We have to be ready, there are still a lot of things to improve.
"It's a question of team effort, the intensity that we are willing to give, the closeness that we play all together against the ball, the sacrifices that we are willing to make.
"If we are willing to make sacrifices, if we are willing to go over all obstacles, then for sure we are ready.
"But if we have big spaces, if we don't all play together, for sure we will not be ready."
Kylian Mbappe was earlier the star of the show once more for PSG, scoring an eye-catching first goal in sweltering Suzhou.
Strike partner Edinson Cavani also scored in the first half before substitute Metehan Guclu netted with a clever flick a minute from time.
In the absence of Neymar, who is working his way back to full fitness after injury and could feature on Saturday, the French starlet Mbappe was the focus of attention.
There was a buzz of anticipation each time the 20-year-old prodigy received the ball.
The World Cup winner put Tuchel's side on the way to a comfortable friendly win as he exchanged passes with Juan Bernat before firing beyond Sydney goalkeeper Andrew Redmayne.
Mbappe was subbed at the break as Tuchel changed all his outfield players.