Brendan Rodgers has revealed that Reo Hatate's hamstring injury is a "bad one".
The Celtic midfielder limped off six minutes into the 2-2 draw with Atletico Madrid in the Champions League.
And Rodgers says the Japan international will be unavailable for the upcoming run of games.
"There is not a definitive timeline but he will definitely be out for a few weeks," he said.
"We are just waiting on it to settle down and just waiting on the result and then we will see where he is at but it looked quite a bad one.
"If you watch the game then in the first 35 seconds he is overstretched and he has felt it very early on.
"It is such a shame for him. He was out with a hamstring injury last year and it is his other one this time so we just need to try and get to the bottom of that."
The 50-year-old also opened up on the importance of using his squad well ahead of a busy period of fixtures coming up.
"I am very mindful but you have got to be very robust at that level but I think lots of these players are," he continued.
"You play last weekend and you played midweek and then you have another tough game at the weekend but that is about being a big club.
"Your body is trained for that and you have to prepare for that but there is no doubt over the next few games, as I said last week, we will be making some changes within that."
