Delph has been a key man in recent weeks for the Toffees, using his experience and influence in the middle of the park to help push the side’s bid to survive in the Premier League.
Everton are edging closer to safety in the top flight, but they will be without Delph when they lock horns with Brentford in the Premier League this weekend.
Boss Frank Lampard, in confirming the news, also left it unclear whether Delph will be able to play again for Everton this season.
He is though hopeful on defender Ben Godfrey and midfielder Donny van de Beek, who have been out of action.
“Fabian won’t be fit against Brentford. We will see for the rest of the season”, Lampard told a press conference.
“Ben Godfrey is close. He could possibly be in the squad, Van de Beek is getting closer; I would like to think he could be involved on Sunday.”
Losing Delph in midfield is a blow for Everton, but Lampard will hope he has players who can cover for the absence of the experienced midfielder as the Toffees look to secure survival.