Hearts head coach Valdas Ivanauskas is not yet ready to return to his position at Tynecastle despite completing a two week break for unspecified health reasons.
The former SV Hamburg striker has been recuperating in his native Lithuania since October 23, after agreeing time off with majority shareholder Vladimir Romanov.
Ivanauskas told the Edinburgh Evening News: 'I am feeling better, but not 100%. I'm not ready yet.
'I don't think I will be back as early as next week. I have a medical examination next Tuesday and I will know more after that.
'I could return after that, but I need the doctors' opinions. They say I am okay and looking good but we need time.
'My health is very important because it was so much stress last time.
'I hope my health improves soon and I hope then I can come back.'
It has been a traumatic week for the Edinburgh side since captain Stephen Pressley spoke out about Romanov's interference in the football side of the club, revealing significant dressing room unrest and behind the scene fighting.
Hearts face Celtic at Parkhead tomorrow and have in a top of the table clash that the Jambos must win to have any chance of staying in contention for the SPL title.
Despite being in second place Hearts are already 10 points behind Celtic, and a 13 point gap at this stage in the season would surely be unassailable.
It currently appears unlikely that Hearts will field the team of youngsters Romanov predicted would replace his established players if they failed to beat Dunfermline last Saturday, despite Hearts struggling to a 1-1 draw.
Interim head coach Eduard Malofeev has indicated he will steer the club away from their controversial rotation policy, believed to have been introduced at the behest of Romanov.
Speaking to the Hearts website Malofeev said: 'In my coaching career I have always said that my team must have stability because when you have a stable team you can make good progress.
'If things are always changed then things cannot improve.'
Chilean striker Mauricio Pinilla is doubtful with a calf muscle problem, while forward Roman Bednar is carrying a heel injury.
But Malofeev is confident both players will be available for the trip to Celtic Park.
Celtic are looking to bounce back from their 3-0 Champions League defeat against Benfica on Wednesday night in Lisbon.
A victory tomorrow would extend their winning league run to six games.