Thiago Silva is expected to be out for Chelsea's next two games at the very least, Head Coach Thomas Tuchel has confirmed.
The 36-year-old missed Chelsea's 2-1 win against Sheffield United on Sunday in the Premier League.
Chelsea have now won three consecutive games in the league and remain unbeaten under Tuchel's management.
But without Silva, the Blues were unable to keep a clean sheet after Antonio Rudiger passes it into his own net. It didn't matter in the end as a 43rd minute strike from Mason Mount and a second-half penalty from Jorginho ensured Tuchel's men took all three points.
And Tuchel has revealed the extent of the injury and is hoping to welcome the centre-back back towards the end of the month.
"With Thiago, we are fighting for him every day but he will be for sure out for the FA Cup so it will take time.
"It will be several days but we set the goal, I would like him back for maybe Southampton, that’s realistic but also ambitious. I know Thiago, he will do everything to be ready as soon as possible but it is a muscle injury so you cannot take any risk."
Chelsea will be keen for Silva to return in time for their last-16 Champions League clash against Atletico Madrid on February 23.