"Players have started to realize Novak Djokovic isn't invincible": Serena Williams' ex-coach Rennae Stubbs cites Serb's age as cause for his struggles

Serena Williams' former coach, Rennae Stubbs, recently gave her thoughts on Novak Djokovic's middling form this year. The Aussie believes that while the Serb is keen to adjust his game to win matches, the rest of his peers on the ATP Tour have finally begun to realize that he isn't "invincible".

Djokovic has compiled a mediocre 7-4 win/loss record in 2025 with his best result coming at the Australian Open, where he retired in the semifinals against Alexander Zverev after losing the first set in a tiebreaker. More concerningly, the 24-time Major winner has failed to win a title since going all the way at the Paris Olympics last August.

Seeded sixth at the Indian Wells Masters earlier this year, Novak Djokovic surprised fans as he went out in the second round to Dutch lucky loser Botic van de Zandschulp in three sets. Against that background, Serena Williams' ex-coach Rennae Stubbs dissected the main reasons behind the 37-year-old's recent inconsistency on the latest episode of her podcast, "The Rennae Stubbs Tennis Podcast".

The 53-year-old claimed that the Serb was in the throes of age, insisting that various attributes of a tennis player decline, including footspeed, confidence, and mental strength. She also inferred that having three-time Major winner Andy Murray in his corner wouldn't be an effective solution if the World No. 5 lacks conviction in his game.

"At some point you hit an age where things just get harder. And at 38, you get little bit slower, you get a little bit more nervous, you get less confident, and he hasn't won a tournament since he won the Olympics last year," Rennae Stubbs said on her podcast (from 27:39 onwards). "I just think it's getting harder, and I don't care who is in your corner, you gotta do it yourself."

The former player-turned-coach added that Djokovic's mental edge over the men's field had become less severe over the last few years.

"You gotta convince yourself you're still good enough to win the matches. And these guys are only getter better and better, and the key is that the players, they've started to realize that he's not invincible," she said (28:49). "The mental victory for these players, it's not as hard."

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Serena Williams' ex-coach Rennae Stubbs: "Novak Djokovic has always been the kind of person to break everything down to the minutia"

Novak Djokovic retrieves a ball at Indian Wells Masters | Image Source: Getty

During the podcast, Serena Williams' former coach gave a first-hand account of watching the 24-time Major winner warm up at the tournament venue ahead of his campaign at the 2025 Miami Open. She also touched upon the Serb's routine, which she attributed to his greatness.

"I'm lucky, being on the road now coaching, I get to see a lot of behind-the-scenes stuff, and Novak Djokovic has always been the kind of person to literally break everything down to the minutia," Stubbs said (25:58). "Like we are talking food, diet, training, hyperbaric chambers, travels with specific things... always looking for the edge, which makes him great.

"And to watch him yesterday on the grass area of the Dolphin Stadium, all the players were out there, doing their warm-ups, and Novak was out there, and I saw him standing over there, maybe 20 meters away from me. And he's standing and talking to Andy about something on his forehand. And the amount of times I see him do that on a practice court, or off the court, he just has a session to make something better."

Having received a first-round Bye, the fourth-seeded Djokovic will face Australia's Rinky Hijikata in his first match at the ATP Masters 1000 tournament. The 37-year-old is a six-time titlist in Miami but hasn't enjoyed a triumph at the event since it switched venues to the Hard Rock Stadium in 2019.