The France international is to have surgery on Monday on an ankle injury sustained in training this week, leaving the Toffees boss with only the inexperienced Niels Nkounkou as cover.
Nkounkou, a 20-year-old £240,000 summer signing from Marseille, has appeared in just one Premier League match and three Carabao Cup ties so far.
Ancelotti recently switched to a back three with wing-backs which contributed to Everton ending a run of three successive defeats and that may provide him with a medium-term solution if Digne’s injury is a worst-case scenario.
At Fulham on Sunday midfielder Alex Iwobi impressed as a right wing-back and Ancelotti is open to the idea of playing midfielders in those wide roles.
“It is a big loss because he is one of the best left-backs in Europe at the moment but we have to manage this,” said Ancelotti of Digne’s injury ahead of the visit of Leeds on Saturday.
“I think we will be able to adapt to the loss of Lucas Digne for two or three months.
“Three centre-backs can be an option still. We can use Iwobi on the left without problem as a wing-back so we will see.”
Ancelotti has issues on the other side of his defence as well as Seamus Coleman is still absent with a hamstring injury and Jonjoe Kenny, while available, is not fully fit after three weeks out.
“Seamus is doing his individual rehab and he will not be available for the Leeds game,” the Italian added
“We have Jonjoe on the right. He recovered from his injury, which was not an easy injury. He is not at 100 per cent but is available to play.”
Ancelotti’s original decision to switch to a 3-4-3 system was an attempt to improve their defensive solidity as a leaky backline has seen them now concede two or more goals in their last six matches.
He admits it is still a work in progress and there remain issues to iron out.
“Of course we have to be concerned, we have to be worried, because we conceded too many goals, it is too much,” he added.
“We are working on this. It is true we scored a lot of goals in these first games, we were really efficient up front and our strikers did really well in this period, but we conceded too much.
“We have to avoid this and we have to have, in one word, balance.”
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