Kante is yet to start under the new manager, while Ziyech hasn’t featured since the German’s first game in charge against Wolves last month.
Thiago Silva will miss out as he continues his recovery from a thigh injury.
Tuchel is ready to give chances to a host of players in the FA Cup fifth-round tie, saying: “There is a high possibility we see a lot of changes. There will be guys on the pitch tomorrow who suffer from my decisions in the last games, but they deserve to play.
“It is our third away match in a row and we don’t want to lose intensity. It is the moment to have some fresh legs and fresh minds on the pitch.”
Ziyech has struggled for form in recent weeks since recovering from a hamstring injury.
Tuchel added: “Hopefully tomorrow we see the best in him. He had a good training week.
“We count on Hakim like everyone else. We took some decisions for other players, not against him and he will have the chance tomorrow to show the same quality he shows in training.
“It is clear he needs to adapt to the quality of this league.
“Ajax were the benchmark in the Dutch league, but it is not the same quality and intensity as it is here. He has the quality to decide matches and to give you something unpredictable.
“We want to push him to the same level of performance he gave at Ajax.”
Tuchel revealed when taking charge of Chelsea that Kante was a player he had long desired to sign – but he has preferred a midfield pairing of Jorginho and Mateo Kovacic so far.
Still he insists the France international is key to his plans.
“N’Golo fits into every manager’s plans on the planet,” he said. “I was desperate to have him in my teams. He is a Chelsea player and a big Chelsea player and one of the best midfielders in the world.
“I am so lucky to have him in my squad and so lucky he is back again. He comes back from injury and we put him on the pitch with no minutes against Tottenham, it was really difficult, but he does what he always does, helps everybody on the pitch with his support and his mentality and his quality.
“In the 30 minutes he played against Sheffield [United] was a huge performance when we switched to a three in the midfield. It was very important to be in control of the game again.
“I know him for many years, we were very impressed from television but to see him live, how he works, how humble he is, it is a gift to be his coach. I am super happy.
“He will start tomorrow. For me his best position is a double six. He can play single six, but if he plays a single six you have to be more disciplined in his position.
“He can do this, but it would cut his wings a bit so double six is his best position. If we keep the structure we have in the last games it suits him very well. The distances are close to use his strengths in counter pressing and recovery of the ball. He is an outstanding player.”
Chelsea predicted XI (3-4-2-1): Kepa; Zouma, Christensen, Rudiger; James, Kante, Gilmour, Chilwell; Ziyech, Pulisic; Abraham