Novak Djokovic said Serena Williams is 'one of the greatest ever' in all sports

• Novak Djokovic is headed to the 2021 Australian Open men's championship match.
• Serena Williams won't be competing in the final on the women's side after losing to Naomi Osaka.
• Still, Djokovic knows "she's one of the greatest ever ... athletes, not just tennis players."

Novak Djokovic knows a GOAT when he sees one.

The Serbian superstar locked in his spot in the 2021 Australian Open men's championship match after taking down Aslan Karatsev in straight sets on Thursday. And though fellow tennis great Serena Williams fell short against Naomi Osaka in their blockbuster semifinal match, Djokovic still took time to acknowledge the 23-time Grand Slam champion's greatness in his post-match press conference.

"She is such an amazing champion that inspires both male and female athletes around the world," he said. "And what she has been doing - still is doing at her age - is extraordinary."

Djokovic said he could relate to the pressure Williams faces while "chasing big things that are related to the history of the sport." Since stepping away from the court to give birth to her daughter, Olympia Ohanian, Williams has been chasing her highly-coveted 24th major championship, which would tie her with Margaret Court for the most Grand Slam titles in tennis history.

Williams' straight-set loss to Osaka on Thursday marks the sixth time she's lost in the semifinals or finals of a major tournament since the 2017 Australian Open victory that gave her Grand Slam title number 23. Djokovic - who has a whopping 17 Grand Slam titles of his own - said that he "can empathize with Serena and what she's going through" and that her disappointment is "completely understandable."

"I'm sure she's disappointed - I heard she was also emotional in the press conference," Djokovic said. "Regardless of all the success she's had, I know that when you lose a big match, you are frustrated. You're pissed off."

Even despite Williams' recent struggle to break through for No. 24, Djokovic said it's still a "thrill" to "experience her greatness" and that he's "proud and honored to be playing at the same time" as a living legend. He recognizes that her legacy transcends any one record - and even any one sport.

"She's one of the greatest ever," Djokovic said. "There is no doubt."

"Athletes, not just tennis players," he added.

Check out the full clip of Djokovic's comments about Williams below: