It puts him in line for his first involvement in a Chelsea squad since being named as a non-playing substitute against Atletico Madrid last month.
Tuchel said: “Tammy was with the group today. We had a bit of a scary moment because he stumbled again a twisted his ankle. It was a painful moment, but hopefully nothing too serious. I hope he is in the squad on Sunday.”
Thiago has not played since limping off against Tottenham at the start of February.
Tuchel added: “Now is not the moment to take a risk with him as it’s the last game before the international break. We have two weeks.
“It’s already too long (without him) but I know how hard the medical team is working, how reliable everyone is. So zero complaints.
“We are just wishing for him to feel 100 percent free, so we are taking our time. He is in individual sessions and hopefully, he can rejoin the group during the international break and be ready for the decisive part of the season.”
Olivier Giroud is in contention to start. The Frenchman has made just one appearance since his stunning winner against Atletico.
Tuchel said: “I think he can have a huge impact in our team because he has the experience, the physical presence and ruthlessness in the box. That is his style of football.
“He has suffered in the last four games a bit and I am not so happy with my decisions against Southampton and Leeds.
“After the game, I had the feeling they were games that he should’ve had 20-25 minutes to help us win rather than draw. I didn’t give him these minutes because I have to adapt back to three changes, which is maybe two changes because the last one you don’t want to use too early. So it’s clearly my fault.
“He is training well, had a decisive goal against Atletico, and I assumed the games against Everton and Liverpool would be high-intensity games where we could use speed more. That isn’t his biggest strength and there’s no problem with that.
“He will stay positive and it is my job to push him and give him the feeling that he is still important because he important for me.
“So the game on Sunday is the next moment. The international break is a good time for Oli to keep his head in the clouds and enjoy this moment with us. I know he is a big part of the dressing room and I want him to continue like this.”
Chelsea predicted XI (3-4-2-1): Kepa, Azpilicueta, Zouma, Christensen; Hudson-Odoi, Jorginho, Kovacic, Chilwell; Mount, Werner, Giroud