Originally raised in Austria, Kovacic moved to Dinamo as a 12 year-old from Linz.
He told chelseafc.com: "We had an amazingly talented generation where I played. A lot of players I played with at the Dinamo Zagreb academy are now playing in huge clubs, people like Andrej Kramaric, Alen Halilovic and Sime Vrsalijko. Croatia is a country with really talented players, but we lack the will to work! We don't work so much, but from Dinamo Zagreb many players did good and for me it's one of the best schools in Europe.
"I broke my leg when I was 14. That was a part of my career that was difficult. It was difficult for me, but not just me, also my family. They had moved and sacrificed everything, and then maybe it was over. It was a huge punch for us, but we believe in God and we knew I would come back for sure.
"And I did. I came back very strong, and when I was 16 I went to the first team. That was my first step in professional football."