The Blues striker clattered into the advertising hoardings during the 2-2 draw with Arsenal and looked in considerable pain after the final whistle.
Abraham, Chelsea’s top scorer this season, will not make the trip to Hull for the FA Cup fourth-round clash on Saturday – which you can hear LIVE on talkSPORT.
“The good news is he hasn’t fractured anything, but the other news is we still have to see how he develops,” said Lampard.
“He’s not fit for the weekend, but whether he’ll be fit for Leicester I’m still not sure. It’s still not clear at the moment.”
Abraham’s absence only strengthens the need for attacking reinforcements at Stamford Bridge.
Last week, Lampard refused to dampen speculation about a move for PSG’s Edinson Cavani, and today he continued to fuel rumours about the arrival of a new striker in the coming days.
Here’s everything the Chelsea manager had to say about that and more…
Lampard on transfers
“I think the impetus to bring in a striker or players potentially that can get on the end of these chances we’re creating is there, we have to be honest.
“When you’re creating 20 chances a game and not scoring enough goals that can be crucial. I don’t think it absolutely changes it but Tammy has been our main source of goals, so yes, it’s very relevant.
“I think there’s choice [in the transfer market], but it’s not the ideal window, history has proven that.
“I think it’s about trying to get the choice right of the player we can bring in considering what’s available.
“The club know, and the games are showing, my thoughts on that. So we’ll have to see how that goes between now and the end of the window.”
Lampard on Kepa’s struggles
“He will have to deal with that. That's what being a footballer is about. There is spotlight on them.
“The important thing for that is not to get embroiled in what people are saying, not just Kepa but any player.
“I am not looking at strengthening that position now. Kepa knows and is honest that there have been some mistakes.”
Lampard on Chelsea’s recent form
“I am not happy, it's the fact we could be in better daylight in fourth.
“In the last two games alone, we have created chances. Newcastle two shots and a goal, Arsenal two shots two goals. We need to get that right.”
Chelsea boss Frank Lampard admits that while Tammy Abraham’s ankle isn’t fractured, the club are still sweating on the severity of the injury.