N'Golo Kante will miss Chelsea's trip to Wolves on Saturday and remains a doubt for matches against Valencia and Liverpool next week.
Kante missed both of France's fixtures during the international break with an ankle injury and a return against Wolves is "too soon", manager Frank Lampard confirmed on Friday.
Chelsea play Valencia in their opening Champions League match on Tuesday, before hosting Liverpool next Sunday.
"I don't want to jump the gun because we're waiting for improvement to fill that final step to get him to where we want him to be on the pitch again," Lampard said. "But hopefully that will be in a week or so."
Hudson-Odoi, James back for U23s
Callum Hudson-Odoi and Reece James will play for Chelsea's U23 side on Friday after injuries.
"They’re two young players that are going to be big for this club going forward – we’ll be watching," said Lampard.
Mateo Kovacic (Achilles) and Pedro (hamstring) are fit to play against Wolves, while Antonio Rudiger will be available after recovering from a knee injury that ended last season prematurely for the defender.
Chelsea have conceded nine goals in their four Premier League matches this season, with only Norwich having a worse record.
"It's a choice for myself, but he will have an important role," said Lampard, when asked if Rudiger would go straight into Chelsea's defence. "We have missed him as we have with a few more front-line players.
"I don't want a young team for the sake of it. He can be influential. He is ready to take on those roles."
Lampard warns Mount: Expect increased scrutiny
Lampard said he was "proud" to watch Mason Mount make his England debut during the international break, but put pressure on the 20-year-old to keep up performances.
"This is where the scrutiny ramps up," said former England and Chelsea midfielder Lampard.
Tammy Abraham, 21, also received a warning not to let rivals seize his spot in Chelsea's starting line-up - after four goals in his last two matches.
"I want more, he wants more, they want more - and they'll have to," said Lampard. "[Olivier] Giroud, [Michy] Batshuayi - they all want that position so they all need to be on their toes."