Chilwell played a starring role in the Blues' Champions League final win over Manchester City just four months ago and was a mainstay in Chelsea's XI when Tuchel was appointed Frank Lampard's successor in January.
However, that triumph in Lisbon was surprisingly the full-back's last competitive match, with Gareth Southgate not using Chilwell at all during England's run to the final of Euro 2020, and Marcos Alonso playing in Chelsea's four Premier League games and European Super Cup win.
Blues boss Tuchel says the early season form of Alonso has made Chilwell's situation even more difficult but is confident he will come back fighting.
"It has been difficult for him. It's pretty normal, he came from the Champions League win and 90 minutes and a strong performance and had a strong end to the season with many important games on a high level," Tuchel said ahead of the start of Chelsea's Champions League defence against Zenit.
"Then it was personally a tough Euros, there were chances when he thought he could have played. Personally, I know it was a tough one, you feel he did everything to push the team, you don't feel it if you don't sweat it out and put on the shirt.
"Then to keep also training for four-five weeks continuously, then he had a break, it's hard to totally relax and get this personal disappointment off the shoulders.
"When he arrived back here, I felt him a bit mentally tired, a bit still worrying about the situation. At the same time he had to accept he was very unlucky I think during the start of the season because Marcos was here all pre-season, did every session, and took the opportunity so, so great with a great attitude, he was crucial to us and delivered in Chilly's situation.
"I had some talks with Chilly and in the same situation he knows I would have done the same thing if the situation was the other way around. They push each other, I have no further worries with Chilly.
"He has to be patient, keep training, I had to give him a little time to be patient with himself to find joy again and find things a little easier on the pitch, not force it too hard. This is where we are now.
"Unfortunately, we only had three subs in the last three games otherwise he would have had some minutes."
With Chelsea able to name 12 substitutes against Zenit, the likes of Ruben Loftus-Cheek, Ross Barkley and Malang Sarr may have the opportunity to press home a case for minutes.
Tuchel says anyone in the squad must be ready to play at any moment.
"It's very easy. If you get registered, it's your duty to be ready. When you get dressed at Chelsea every day, it's your duty to be ready," he added.
"When you step in the building and training pitch, you have to be ready. It's the baseline for everything. No one gets a gift here.
"Malang is here, Ruben is here, Ross was in the squad against Aston Villa. We have a tight group, a high-quality group, they did now a first step and for whatever reason they did not find other clubs, or accept other clubs, now they deserve the next steps and to be part of this group. Once you're in this group, you have to match high expectations we have on ourselves.
"You have to be ready, when in the group you have to be match ready, I have the feeling they are.
"They are showing good mentality and put personal situations aside. From here no promises are made but anything could happen."