Everton will be without seven first-team players ahead of their second leg tie against Hajduk Split.
The Toffees will travel to Croatia for their return fixture, holding a two-goal lead, after Michael Keane and Idrissa Gana Gueye netted for the home side at Goodison Park.
Everton will be considered favourites to advance to the next stage of the Europa League, however, Ronald Koeman will have to do it with a depleted squad, as injuries are running rife through the Merseyside outfit.
The Dutchman has confirmed Davy Klaassen and Sandro Ramirez have stayed in England and will continue to recover from injuries that they have picked up in the past week.
â€œSandro did not travel and neither has Davy Klaassen, who got a knock on his foot,â€ he told the clubâ€™s official website.
â€œDavy will be out for at least one week but he will be fit after the international break.
â€œSandro is a doubt for Sundayâ€™s game [against Chelsea].â€
Koeman also confirmed that James McCarthy is still unavailable for selection due to a knock he sustained to his knee, believing he should be ready after the international break as well.
â€œJames McCarthy has a knock on his knee and, also, normally after the international duty, he will be available,â€ he added.
Ramiro Funes Mori and Yannick Bolasie both remain sidelined with knee problems themselves, however, they are out for the long-term, whilst Seamus Coleman is nursing a leg issue.
The injury list does not stop there for Everton, with Ross Barkley out with a hamstring injury, although it is doubtful the England player will be at Goodison Park come to the end of the transfer window.
Despite all the injury issues Koeman is facing, he will be able to call upon Gylfi Sigurdsson for the tie with Split, suggesting he will get some time on the pitch, although he does not know if it will be in a starting position or from the substitutes bench.
â€œHe got game time on Monday and now the decision is whether he starts tomorrow or comes on during the game,â€ he added.