The 32-year-old Serbian star had just won the men's singles quarterfinal match against Canada's Milos Raonic at the Australian Open on Tuesday when he was asked about the late NBA star while being interviewed by John McEnroe.
Djokovic, who wore a green jacket with the initials "KB," a heart, and Bryant's two numbers, 8 and 24, stitched on it, spoke about his friend.
"I don't know what we could say. It really caught us by surprise," he began. "He was one of the greatest athletes of all time. He inspired myself and many other people around the world."
Though Djokovic didn't go into specifics, he did note that he had a "personal relationship" with Bryant for the past 10 years.
"When I needed some advice and some support, he was there for me," he said. "He was my mentor, my friend. It's just heartbreaking to see and to hear what has happened to him and his daughter."
Djokovic got visibly emotional, putting his hand over his face as the crowd cheered their support.
ET previously confirmed that Bryant and his 13-year-old daughter, Gianna, were two of the nine victims in a helicopter crash in Calabasas, California, on Sunday.
On Monday, Djokovic took to his Instagram account to share a photo of himself with Bryant.
"My heart truly mourns over the news today. Kobe was a great mentor and friend. There are not enough words to express my deepest sympathies to the Bryants and every family suffering from this tragedy," he wrote. "May God bless you and your Gianna. Thank you for being there for me and inspiring the entire world. Thank you for showing all of us athletes how to compete and respect sport. Thank you for the greatest legacy you leave behind with us. I’ll never forget your smile spreading positive energy everywhere you went. You and your daughter will live forever ♾ in our hearts ❤️. RIP amico mio. Ti voglio bene."