Borussia Dortmund will be without Mario Gotze for their DFB-Pokal clash with Eintracht Trier on Monday, while Marco Reus' return from injury has been delayed.
Gotze did not feature in Dortmund's DFL-Supercup defeat to Bayern Munich last week but played the majority of last Monday's 3-0 friendly win over Sandhausen.
However, an adductor injury sustained in training means he will not be risked for the trip to Moselstadion, with Christian Pulisic replacing him.
"Mario Gotze has complained about a slight adductor problem after training on Sunday morning, which is best described as muscle tightness," Tuchel told a media conference.
"As a precaution he will not play at Trier. He worked very hard over the last week. Christian Pulisic will take his place in the squad."
Gotze represented Germany at Euro 2016, however team-mate Reus was not present having suffered an adductor injury of his own.
The attacking midfielder was expected to return to training in mid-August, but Tuchel is keen to avoid taking any risks.
"The first reintegration point we had envisaged passed a few days ago. Caution enjoys the highest priority," he said.
"Since we have not counted the days and obsessively pushed for deadlines, I am only able to say he returns when he does.
"If there is still a risk, we prefer to take a step to the side. We have therefore shifted his return back by a few days."
Roman Burki was Tuchel's first choice goalkeeper in domestic competitions last term, but the coach confirmed Roman Weidenfeller will be used in the cup this time around.
"Roman Weidenfeller will be in goal for the DFB-Pokal games this season," he said, before expressing his confidence in the team and their work ahead of the new season.
"I am very satisfied with the performance in training this week. We trained in a great mood.
"The level is rising steadily. The base is the effort in the Supercup, and now we want to continue to improve.
"I have full confidence in the team."