MIAMI — After two decades of professional tennis, 99 career singles titles and 24 Grand Slam triumphs, Novak Djokovic has become a mystery — to tennis fans and to himself. Both parties are trying to answer the same question, from match to match and tournament to tournament, as his career moves towards an as-yet unknown end.

Who is the greatest player of the modern era at this moment?

Is he the player who faded two weeks ago against Botic van de Zandschulp, in his opening match at the BNP Paribas Open at Indian Wells, Calif.? Or is he the player who has plowed through his first three opponents in at the Miami Open the past five days, including Lorenzo Musetti, the world No. 16 from Italy?

Is he the player whose return of serve, one of the greatest in the sport’s history, has been a shadow of its usual self? Or is he the player who broke Musetti five times Tuesday night on his way to a 6-2, 6-2 win?

Is he the player ramping up his schedule as he approaches his 38th birthday, because it’s his last spin around the tennis globe? Or is he the player he described to the Miami crowd when he told them, “You’re going to be seeing me a few more years.”

When it comes to the subject of Novak Djokovic, Djokovic is like everyone else: always searching for the signal in the noise, searching for the data about himself and his tennis that will allow him to separate what matters from what does not. At this moment, there is both too much and not enough data to figure out who and what the Djokovic of 2025 is. All these years later, but just 14 matches into this season, he has become the sport’s international man of mystery — definitively not what he once was, and searching for the answer of what he will be.

“I do hope and wish for Novak that you saw tonight, and then at the same time, I worked hard not to have the Novak that was playing in Indian Wells,” Djokovic said in the mixed zone with reporters when his match with Musetti was over. “The continuity or consistency of the level of tennis nowadays for me is more challenging than it was years ago or 10 years ago, five years ago, and I know that.

“That’s definitely not due to lack of hours spent on the practice court and in the gym because I still keep the dedication. It’s there, but it’s just makes it a bit more challenging for me to maintain the level.”

Djokovic is living through a common misconception about what happens to elite athletes declining from their peaks. The apexes stay sharp and accessible in fleeting moments, even when they need them most: Djokovic found his on his otherworldly run to the gold medal at last year’s Paris Olympic Games. It’s the stability that erodes, the repetitions that are necessary to maintain their excellence.

Djokovic’s biggest triumph this year came at the Australian Open, where he beat Carlos Alcaraz in the quarterfinals after a series of wins that had included serious dips in his level, during which young and inexperienced opponents found ways to hurt him but could not finish him off.

Stunning as it was, the victory was also one of the strangest tennis matches in memory. Djokovic suffered a muscle tear in the first set, but somehow managed to win in four, thanks to a heady cocktail of painkillers, adrenalin and an inexplicable Alcaraz breakdown. The Spaniard succumbed to the stress of playing Djokovic, of thinking about his opponent’s tennis and his physical condition more than he was thinking of his own.

Three days later, Djokovic had to retire from his semifinal against Alexander Zverev at the end of the first set because of his muscle injury. When he arrived in Florida, he had not won a match since beating Alcaraz on that January night in Melbourne.

In Miami, he has wins against Rinky Hijikata, a 24-year-old Australian who has played 13 Grand Slam matches, just over half the number of Grand Slam titles that Djokovic has won. He then beat Camilo Ugo Carabelli, a 25-year-old Argentine who has never won a Grand Slam match.

Both matches opened with a blowout set and ended with Djokovic winning a tiebreak. It’s one of the most familiar patterns in Djokovic matches over the years, just inverted: the tight set to loosen everything up before the acceleration to victory swapped for a fast start and then an ebbing end.

Then came Musetti. On paper, he looked like a legitimate threat. On the court, Djokovic picked up his head and saw Serena Williams sitting in the stands. He looked at his box and saw Andy Murray and Juan Martin Del Potro, the retired Grand Slam champions. One his coach; the other his good friend. All those big names made him a little starstruck and nervous about playing well, especially in front of Williams, the greatest female player of all time.

Musetti’s elegant all-court game suits grass, clay and slow hard courts, but he remains reasonably lost on fast ones. Against the best hard-court player in the history of the sport, he broke serve in the first game and surged to the illusion of a 2-0 lead built on making the match physical. Djokovic decided he wasn’t going to play a match like that and won the next nine games to seize control. Musetti showed about as much resistance as a swinging door.

On Wednesday night, Djokovic will face Sebastian Korda, the young and talented American of a thousand renaissances, seemingly always on the cusp of announcing himself. Korda, 24, is still trying to find his way after a couple of years of wrist injuries; he received treatment on his wrist during his round-of-16 win over Gael Monfils on Tuesday.

Djokovic won their only previous meeting, in Adelaide, Australia, two years ago. He might get some more data about their matchup and about himself Wednesday, but it’s not clear how fit Korda will be to give him what he needs. Djokovic at least has no doubts about his wants: to keep playing at the highest level in an era when even the youngest players approach the game with a level of professionalism unheard of when he was starting out.

“Fitness and recovery and just overall approach to the work, from both physical and mental side has improved so much,” he said in Miami.

“Nowadays, pretty much every player in the top 30 in the world has a full team of three and four people around them that takes care of them, their body and everything, so that that reflects on the court. That’s why the careers are extended now.”

When he embarked on his professional career, players started counting their days when they hit 30, he said. Now it’s more like 35, maybe more.

“Of course I’m in that group. I’m not going to get younger, but I still feel good about my body and about my tennis.”

That may be the data point that matters more than all the others.

(Top photo: Al Bello / Getty Images)