Not setting foot on court to train on a rest day at a Grand Slam might seem unwise, but it is one of the routines that works best for Carlos Alcaraz, and one of the keys to many of his triumphs.

The Spaniard will play on Wednesday in the quarter-finals of the US Open against Alexander Zverev without having practised on Tuesday. He used the same routine before playing his fourth-round clash with Matteo Arnaldi, and it is one he has employed at many events throughout his career.

“There are days when I dedicate my time to fitness and not tennis,” explained the Spaniard, who has a 15-1 record in the season’s final Grand Slam, where he is defending the title he claimed in 2022, his first major and the key that opened the door for him to become the youngest No. 1 ever in the Pepperstone ATP Rankings. “There are a lot of days when I prefer to work on load training and fitness, rather than practise tennis.”

Not practising on a rest day at a tournament is not something Alcaraz is trying for the first time at this US Open, far from it. Last year, at Flushing Meadows, the Spaniard chose not to pick up his racquet the day between matches. It was a roadmap that allowed him to come through the demands of three consecutive five-set matches unscathed; the fourth round against Marin Cilic, the quarter-finals against Jannik Sinner and the semi-finals against Frances Tiafoe. This year, at Roland Garros, he did not practise a single time between matches, nor did he at Wimbledon as the final rounds approached (before his semi-final and final).

“Mentally, getting tired of winning, of travelling to play tennis, I’m not worried about that because I know it won’t happen to me. What really worries me, so to speak, or what might be a concern for me in the future, is injuries,” explained Alcaraz, all too aware of what he has to do to stay fit in the face of the demands of playing at the very top of the game.

“I haven’t been training on the days I haven’t played and it’s worked well,” he said a few months back in Paris, during Roland Garros. “I’m doing things very well and I feel good. Mentally, I’m fresh. Why change things if it’s working?”

It is certainly unusual; most players will practise tirelessly on their days off in a bid to fine-tune their games and not lose their touch. But Alcaraz has proven that it is possible to aspire to everything by taking a day off when he has no matches, because sometimes resting is also training. This is the message drilled into him by Juan Carlos Ferrero, his coach, and Juanjo Moreno, his physio and the man responsible for looking after Alcaraz’s body.

Not practising at Flushing Meadows does not mean having a free day, of course. As well as working in the gym at his hotel, and receiving treatment on the recovery stretcher, Alcaraz takes the opportunity to spend time with his family and team in New York. For example, on Sunday he took the chance to wander the streets of Brooklyn, while on other days he has visited Central Park to have some contact with nature and get away from the hubbub of Manhattan.

Alcaraz needed eight hours and 36 minutes of tennis to reach the quarter-finals of the US Open, dropping just one set along the way to Daniel Evans. He trails Zverev, his next opponent, 2-3 in their Lexus ATP Head2Head.