Forster has stepped up after the ankle injury suffered by No1 goalkeeper Guglielmo Vicario last week.
Ahead of today's derby against Fulham. Kulusevski told the Independent: “I think he is a top guy, with unbelievable experiences and I trust in him.
“He is a really good guy to have around the team. He is ready to play and I feel also confident we have Brandon Austin, a very good goalkeeper.
“So, yeah we miss Vicario because he is a fantastic guy and everything, but now it’s time for Fraser to step up and help the team.”
- Get breaking football news faster with the new Tribal Football app! Download now on iOS and Android to stay ahead of all the latest transfers and football updates. Download now: App Store, Google Play
