Kante went to ground with a muscle injury in Chelsea's 2-2 draw with Tottenham Hotspur in the Premier League and Tuchel had said he was not optimistic about the World Cup-winner's availability in the coming weeks.
"It's difficult to replace him, he's unique. We were full of hope for the pre-season... He felt strong and he had enough rest and build-up to be the player he can be," Tuchel told a news conference before Saturday's game against Leicester City.
"We started with one game a week and the hope was that he could play for us. We have trust in our players so it'll be the same system.
"We have played many games without him in the structure but we understand the challenge. To change completely because N'Golo isn't there, I don't think so."
Midfielder Mateo Kovacic (28) is back training following a knee injury. "We need him long term but it's good to have him as an option," Tuchel added.
The German manager said he expected his team to respond to their 3-0 defeat by Leeds United last time out.
"Because we don't like to lose and as painful as it is to analyse and look again, it's important," Tuchel said. "We always get a response once the reasons are clear.
Tuchel said Chelsea were looking to bolster their squad before the transfer deadline of September 1.
"We have some ideas but maybe nobody comes in. It's not a long window anymore," he said.
