The duo limped out of training on Wednesday and underwent scans to assess the nature of the injuries.
Thomas Tuchel confirmed both could be out of Thursday’s crunch game.
But he can welcome back Ziyech, who was left out of the squad for Sunday’s win against Burnley on the advice of Chelsea’s medical staff.
The German said: “We had two little issues today on the training pitch. It was Kurt Zouma and Kai Havertz who went off the pitch with little issues so they are checking issues and doing images right now.
“It is questionable if they are in the squad for tomorrow. Everyone else is available.”
Tuchel faces Jose Mourinho for the first time as a manager and revealed his admiration for the former Chelsea manager.
“I think it is very clear what he stands for,” he said. “He builds competitive teams. He builds strong teams.
“He has now built a Tottenham squad with characters like (Moussa) Sissoko and (Pierre-Emile) Hojbjerg who support the defence. They are super competitive, defensive, disciplined, hard-working guys. They have up front normally Harry Kane, Son (Heung-Min), (Steven) Bergwijn, (Erik) Lamela, (Gareth) Bale.
“They have outstanding quality and speed and I have the biggest respect for him because he is building teams on the highest level to compete and to win game after game after game.
“This is what he’s doing at Tottenham and we are doing it in our style and our beliefs. Everything is allowed. There are many ways to succeed.
“I think he was very successful to believe in himself and until today he has an outstanding career. He is a world-class coach and we are here to beat him tomorrow with this squad.
“This is the challenge we are up for and we are very excited to have matches like this.”
Chelsea predicted line-up: (3-2-4-1) Mendy; Azpilicueta, Thiago, Rudiger; Kante, Jorginho; Hudson-Odoi, Mount, Pulisic, Alonso; Giroud