But Frank Lampard is confident the pair will be back for the hectic Christmas and New Year schedule.
Both wingers have now been assessed by Chelsea’s medical team, with Lampard optimistic about their conditions.
He said: “Both players are hopefully going to be out for around two weeks. They had scans yesterday and their injuries are showing that they will be about two weeks.
“I think that’s positive. Particularly with Hakim it’s positive.
“With Callum we didn’t know what to expect. It was an injury he got in training a couple of days ago.”
It means Lampard will have to tweak his lineup for Saturday’s game against Everton, with Timo Werner or Kai Havertz potentially playing on the right of attack.
Havertz was deployed there in the 1-1 draw with Krasnodar, which ensured Chelsea remained undefeated in the Champions League group stage.
Lampard added: “I was happy. It was a tough game to navigate. Nothing on it as such other than our own attitude and how we perform and how we approach and I thought our attitude was great.
“No injuries, minutes for players, Billy Gilmour back in the side. Tino Anjurin debut at this level, so all around I’m very content.”