He's 39 and is a 24-time grand slam champion who now plays only sparingly.
So he's better positioned than almost anyone else to analyse what Serena Williams - a seven-time Wimbledon singles champion just like he is - must have been feeling after losing at the All England Club earlier this week in the first singles match she has played in nearly four years.
"People always expect you to play at your best because they're used to seeing you dominate the sport for many years," Djokovic said.
"She's 44. She has two children. Coming back, it's normal that she still is not at her best in terms of movement. She hasn't played a match in so many years.
"People need to cool off a little bit with judgment and criticism and everything. Let's just enjoy the greatness, who she is, what she represents to the sport."
Williams was beaten 6-3 6-7 (8-6) 6-3 by 20-year-old Australian Maya Joint in the first round on Tuesday, but showed she could be competitive with an opponent less than half her age after being away for so long.
Williams still cranked out serves faster than 120 mph and dictated points with her heavy groundstrokes. But movement was an issue and the 87th-ranked Joint was able to win more of the big points by hitting beyond the reach of the 23-time grand slam singles champion.
"Her wanting to give it a try and just come back is an incredible gift for our sport," Djokovic said. "I think people sometimes - I don't know why - they don't appreciate that enough.
"They just start to speculate, judge or whatever. It's like, 'Hey, guys, enjoy. You have the greatest ever to come play for you, to bring more attention to your sport.'
"I really support Serena. Always have. Hopefully she's going to play more," Djokovic added.
Williams was given wild card invitations to play both singles and doubles at Wimbledon and it remains to be seen whether she will still play doubles with older sister Venus.
Williams announced on Wednesday she had tweaked her right knee toward the end of the first set against Joint.
She said she still hopes to play doubles but the Williams' sisters opener against Colombia's Camila Osorio and Solana Sierra of Argentina was only the remaining first-round match not on the schedule for Friday. There's is still a possibility they could play Saturday.
At last year's US Open, Djokovic publicly challenged Serena to return.
"When somebody challenges her, she never refuses. So I challenge Serena: Come back on the tour next year," Djokovic said in 2025.
Now, Djokovic wants to see Serena play at this year's US Open.
"I hope for the sake of tennis and all of us that we be able to see her more," Djokovic said. "I assume that US Open is somewhere where she would like to play. Playing in her home slam would be amazing for her and for everyone else.
"What she's doing is incredible. Epic. "I've always been a fan of Serena. I'm sure she wanted and expected to at least win one match or more.
"Knowing how competitive she is, the mind of a champion that she has, she's not happy with just showing up on the court. She wants to win."
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