Chelsea midfielder N'Golo Kante aggravated an existing ankle injury in Saturday's 1-1 Premier League draw with Liverpool, manager Thomas Tuchel said, leading to the France international being substituted at half-time.
Kante initially picked up the injury in the warm-up ahead of the UEFA Super Cup earlier this month and was not involved in Chelsea's Premier League season opener against Crystal Palace as a precaution.
He made a substitute appearance in last weekend's London derby win against Arsenal, but Tuchel said the injury flared up again following a challenge from Liverpool's Sadio Mane. He did not provide a timeline for the 30-year-old's return to action.
"He is injured. He missed the Arsenal game because of pain in his ankle and some inflammation, but it was nothing serious obviously because he was back in training and he started (against Liverpool)," Tuchel said.
"In winning the ball in this situation, the opponent fell on his ankle and twisted it again. He immediately had the same pain he had before the Arsenal game and he was lacking the force to accelerate and we had to take him off.
"Can there be any harder challenges than going one man down and taking N'Golo Kante off at the same time at half-time at Anfield and having Liverpool playing towards the Kop? But we did excellently and we are super happy... we deserved the point."
Chelsea will take on Aston Villa in the Premier League on Sep 11.