The teen made his Sweden debut this week as Kulusevski wore the captain's armband.
Kulusevski said: "First of all, it's so fun to have him here and it's the first time I've had a Swedish team-mate here at the Club," Deki beamed. "He's still very young. I remember when I was his age and, when I see another youngster here, I feel like I can help him settle in and progress quicker because I've already done what he's doing right now.
"It's very nice to have him here and with me on the national team because he deserves to be there. He's doing really good and he came very well prepared physically. Then mentally, he's just a young man who wants to express himself playing football and that's a good quality because it's important that he has fun when he's playing.
"I think for us around him, the best way to help him is to not give him too much information - just let him play football as he's a very good player and that's what I'm trying to do to help him. When people tell me to help him in different ways, I'm very protective of telling him too much because I just want him to have fun and enjoy it - I don't want to put any unnecessary pressure on him because he's very young."
Sweden have enjoyed a positive week by winning against Azerbaijan and Estonia in their Nations League ties.