Manuel Pellegrini has made two changes to his team as West Ham face Crystal Palace as Manuel Lanzini and Roberto come into the side.
The former Manchester City boss has opted for Roberto ahead of David Martin, with Fabianski thought to be out for less than three months after being forced off against Bournemouth.
The Hammers boss is confident in the Polish international's deputy.
He said: "About Lukasz, the medical staff will decide today or tomorrow if he will have surgery or if he will recover without surgery.
"Either way, it will be less than three months he is out.
"For the moment, we have Roberto as goalkeeper and I trust a lot in him. I am confident he will have good performance. We also have David Martin, who has good experience."
Lanzini returns to the starting XI in the place of Pablo Fornals. The Argentina international has faced the Eagles five times in his West Ham career and scored four times, while the Irons have remained unbeaten in those games, winning three of them.
Michael Antonio remains out injured after undergoing surgery for his hamstring injury in September.
Palace remain unchanged other than James McCarthy replacing Luka Milivojevic who is suspended after picking up five yellow cards.
West Ham XI: Roberto; Fredericks, Diop, Ogbonna, Cresswell; Rice, Noble, Yarmolenko, Lanzini, Anderson; Haller
Crystal Palace XI: Guaita; Ward, Kelly, Cahill; van Aanholt, McArthur, Kouyate, McCarthy; Zaha, Ayew, Schlupp
