Kisfaludy told The Sun: "I worked with him when he was nine-years-old until 14. And directly after the first training session I was thinking 'oh s***, this is something special'.
"He has always been the wonderkid that everyone is speaking about.
"I have worked in the Brommapojkarna academy for so many years; we had Gyokeres, Kulusevski, John Guidetti and Ludwig Augustinsson but Lucas has the most talent of anybody. He always had fantastic technique. And he is scanning the play, always, always the head is up high and he is scanning the play. He always knows what the next step is."
He added: "He was always the boy who if he lost playing seven-aside in the last 20 minutes of training he was totally upset when he was 10-years-old, totally upset. He hated to lose.
"In training he always worked so hard, so he had this special extra thing. He loves to train, he can train 100 days in a row.
"He's a fantastic player with a fantastic charisma. When he walks into a room he is shining."