Chelsea manager Frank Lampard confirmed midfielder N'Golo Kante will not return for Saturday's visit to Wolves in the Premier League and faces a race against time to make Tuesday's Champions League opener against Valencia.
Kante has not featured since a 1-1 draw at home to Leicester nearly a month ago.
"He still has issues with his ankle and the medical team are working with him," said Lampard on Friday.
"He’s in a bit of a transitional period now where we’re trying to get him on the pitch and he’s doing some physical work but this game comes too soon for him."
However, Lampard will be able to welcome back Antonio Rudiger for the first time this season.
The German international centre-back has been sidelined since suffering a serious knee injury in April and will be a welcome addition to a Chelsea defence that has conceded nine goals in their opening four Premier League games of the campaign.
"He’s been very important for the club and the team since he’s been here with his personality, character and quality and we’ve missed him," added Lampard.
"Everyone talks about how young we are and how young we’re becoming so we need leaders within that and Rudiger needs to take on the responsibility of being a leader for us."
Callum Hudson-Odoi is also nearing a return from a long-term Achilles injury and will feature for Chelsea's under-23s on Friday night.
"Callum has been training with us for a while but there are still some issues with the actual injury itself that we need to make sure are okay," said Lampard.
"He’ll need to get match fit so these games are really beneficial for him."