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And Djokovic, who this year has won all three tennis majors with victories in the Australian Open, French Open and Wimbledon finals, said he is hopeful Ibrahimovic can lead the team he supports to more glory.
"I'm always their [Milan] supporter, I'm always Rossonero in cuore [Black and Red at heart] and I'm hoping they can do well in the Champions League and also in the Italian league," Djokovic told Discovery+ Sweden.
"Ibra is a great friend. He's an amazing warrior, a phenomenal champion. He sets a very high standard for everybody -- still at his age after all the injuries he has had, he still keeps on going.
"That's the Balkan mind, the Balkan mentality that drives and succeeds."
Ibrahimovic was born in Sweden to a Bosnian father and Croatian mother and both countries, as well as Djokovic's home state of Serbia, used to be part of the former Yugoslavia.
The Milan forward was due to represent Sweden at Euro 2020 but missed the tournament after picking up a late-season knee injury.
Djokovic is competing in the Tokyo Olympic Games as he looks to add a first gold medal to joint men's record of 20 Grand Slams, having won bronze at the 2008 games in Beijing.