The midfielder picked up an ankle injury on his full debut against Arsenal and has suffered setbacks, including needing a minor operation, but made his comeback to training this week.
When asked whether Mendy would play at the Stadium of Light, manager Claudio Ranieri told reporters: "He's ready and works with us. He made all the training sessions pain free this week. That is good. He lacks stamina because it's not possible 90 minutes, but he's getting better."
Ben Chilwell (ankle) is also back in training, but Kasper Schmeichel (broken hand) and Danny Drinkwater (suspended) are out for Ranieri's side.
Ranieri is hopeful Schmeichel could be back in action before Christmas, the Danish goalkeeper having recently returned to training as he continues his recovery.
He said: "I hope before Christmas Day he'll be ready. It depends on him and the surgeon but his fitness is getting better. He is working on a normal training session, separately."
Provisional squad: Zieler, Hamer, Simpson, Fuchs, Hernandez, Wasilewski, Morgan, Huth, Chilwell, Schlupp, Albrighton, King, Mendy, Amartey, James, Mahrez, Gray, Ulloa, Vardy, Slimani, Musa, Okazaki.