Jeremy Toulalan is a major doubt for Tuesday's Champions League quarter-final clash with Juventus.
The French midfielder pulled up during Monaco's 3-0 win at Caen on Friday and coach Leonardo Jardim has revealed that Toulalan could miss the first leg in Turin.
He told reporters: "I don't know if Toulalan's injury is serious yet or not. We'll evaluate the severity at the weekend.
"He is a really important player for us and our captain, but if he can't be fit to face Juventus then it won't be a problem.
"We'll be able to replace him - after all, he wasn't playing against Arsenal in London and we managed to win that game 3-1."
Monaco's win at Caen moved the side from the Principality up to third in Ligue 1.
