The extent of an ankle injury Tammy Abraham suffered against Arsenal is still being assessed.
The Chelsea striker was helped from the pitch after the game against the Gunners after picking up the injury in the closing stages.
Abraham will miss the FA Cup tie against Hull City but scans have showed there is no fracture.
It is unclear at this stage whether he is likely to be available for the league game against Leicester a week on Saturday.
Frank Lampard explained: “The good news is he hasn’t fractured anything. We were worried about a small fracture or hairline fracture.
“He hasn’t got that, but the other news is that we still have to see how it develops. It’s not a clear-cut one.
“He’s not fit for the weekend. Whether he’ll be fit for Leicester after that, I’m still not sure. It’s not clear at the moment.”
Speaking at a news conference on Friday, Blues boss Lampard also insisted he is not looking to sign a new goalkeeper during the current transfer window despite his recent criticism of Kepa Arrizabalaga.
It follows recent mistakes by Kepa and reports that Chelsea are looking to bring in a new keeper this month – Burnley’s Nick Pope has been touted as a possible signing.
Lampard made it clear he is not looking to replace Kepa “now” but that the Spaniard needs to improve.
“I’m not looking at it (signing a keeper) now and I’m not affected by criticism from the outside,” Lampard said.
“I think with Kepa, he’ll be honest and there have been some mistakes that he’s made that have costs goals. That needs to improve.”
Kepa is clearly under pressure given his poor recent form and the huge transfer fee – around £71m – Chelsea paid Athletic Bilbao for him in 2018.
“He’ll have to deal with that because that’s what football is,” Lampard said.
“Every footballer, no matter how good or great you are, the best – the absolute best of all time – get criticism and that’s what players have to deal with.
“The important thing is to not get too embroiled in what the outside world is saying, and look at yourself and your own game.
“That’s always the basics: how hard can you work? And that’s not just Kepa, it’s any player.
“If you’re lacking form, fight to get it back. Go back to basics.”
Lampard also denied reports that Chelsea are looking to sign Lille midfielder Boubakary Soumaré.
He reiterated the need to sign a striker and said there were no developments in contracts talks with Pedro and Willian or discussions with Inter Milan over a deal for Olivier Giroud to join the Italian club.
This post was last modified on 24/01/2020