Leon Osman will continue to be assessed in the build-up to Saturday’s trip to the Stadium of Light.
Osman was forced off after nine minutes in the 3-0 win over Arsenal with a cut that left him sporting a black eye and needing stitches.
The midfielder has trained with the squad this week and Roberto Martinez said on Tuesday that he would be surprised if the 32-year-old wasn’t fit for the clash with Sunderland.
The Blues boss offered a further update at his Thursday press conference, explaining that he will have a clearer idea whether Osman will be available for selection after the day’s training session.
He said: “Leon Osman is the only doubt that we have from the squad on Sunday . The cut is healing well but the eye is not fully open.
“We need to make sure that it doesn’t affect his vision, so we will have a clear idea after training today .”
Phil Jagielka will again miss out as he continues his recovery from a hamstring injury, though Martinez revealed that the captain will participate in a bounce game later in the week to step up his fitness.
“With Phil being a centre-half, I want to make sure that he is 100 per cent to play 90 minutes,” added Martinez.
“We are going to organise a behind-closed-doors friendly and make sure he plays 90 minutes before he gets involved with the squad.
“He’s been reacting well to treatment and it has been great to have these couple of weeks regenerating and to have given him every opportunity to make sure he is fully fit. We don’t want one per cent of risk of re-injuring.
“I’m hoping that Phil will be available over the next 10 days but it’s dependant on the behind-closed-doors exercise.”
Gareth Barry is one booking away from a two-game suspension after accumulating nine yellow cards.
Saturday’s match is the last before the amnesty, but Martinez says he will not be taking the Manchester City loanee out of the team to protect him from any potential ban at this critical stage of the season.
“I think over the years you learn that there are certain players who can cope with those situations better than others,” added Martinez.
“Gareth has got the experience to play the game and focus on what he has to do without having those issues in his mind.
“It’s important that we focus on the game and the situation with the bookings is something that I’m not concerned with at the moment.”