Wardrobe WHOOPs: Carlos Alcaraz, Aryna Sabalenka run afoul of AO wearables rule

World No. 1 Carlos Alcaraz and No. 19 seed Tommy Paul were set to face off on Rod Laver Arena on Sunday for a place in the quarterfinals, when the chair umpire spotted a banned item hidden under a sweatband on Alcaraz’s wrist.

The item in question was a fitness tracker called a WHOOP band—a now-familiar sight on the wrists of top players at this year’s Australian Open.

Read More: Carlos Alcaraz “suffocates” Tommy Paul, sends American out of Australian Open

Launched in 2015, WHOOP’s low-profile fitness tracker is waterproof and designed to be worn 24/7, making it a must-have for professional athletes and their teams, who use it to track everything from heart rate variability to sleep stages, skin temperature, blood oxygenation, and even detect illness.

It’s been worn by top-flight athletes like Cristiano Ronaldo, LeBron James and Rory McIlroy—and it’s the same device that fellow world No. 1 Aryna Sabalenka was also asked to remove before her own Australian Open first-round match.

Read More: WHOOP and WTA Tour agree to multi-year partnership

Adding to the confusion: All WHOOP devices (3.0, 4.0, 5.0 & MG) have been approved for in-match use by the International Tennis Federation (ITF), and have been an approved staple at WTA and ATP tournaments for years, often worn discreetly under a sweatband.

So what’s the big deal with this tiny, screen-less fitness tracker?

While the trackers are approved under ITF rules—as long as the player can show the device’s haptic feedback is turned off, or that it’s a model without haptic feedback—the Australian Open requires additional tournament-level approval before it can be worn during a live match.

WHOOP founder Will Ahmed called the situation “ridiculous” in a message on social media:

“Ridiculous. Whoop is approved by the International Tennis Federation for in-match wear and poses no safety risk,” Ahmed wrote on X. “Let the athletes measure their bodies. Data is not steroids.”

According to Tennis.com’s gear expert Jon Levey, WHOOP devices are “designed to monitor physiological markers throughout the day and their impact on the body’s readiness to perform… whether it be a tough three-setter or a tense day at the office."

The devices have been a fixture at the top of professional tennis since the WTA and WHOOP signed a multi-year partnership in 2021, making it the first fitness tracker approved for in-match use in tennis.

The ATP approved WHOOP and other wearables in 2024, saying the initiative would enhance player performance, recovery and injury prevention. Since then, the devices have frequently been seen on players, coaches and staff alike, both on and off the court.

It’s no surprise the straps have been spotted all over the courts in Melbourne, as soaring temperatures during the first week have left players and teams more focused than ever on balancing physical stress with proper recovery.

WHOOP issued a statement via a spokesperson addressing the situation:

“WHOOP believes athletes have a fundamental right to understand their own performance and health—including during competition at events like the Australian Open. WHOOP is approved by the International Tennis Federation for in-match wear and poses no safety, fairness or competitive risk.

“Blocking access to personal health data does not protect sport. WHOOP will continue to stand with athletes and our members to defend their right to their data.”

It’s not the first time players have run afoul of the Australian Open’s strict wearables policy. Back in 2022, Naomi Osaka was banned from wearing her signature TAG Heuer Aquaracer watch on court due to its connected smartwatch capabilities.

For now, WHOOP will remain on the practice courts at Melbourne Park, where players like Alcaraz and Jannik Sinner, Sabalenka and Jessica Pegula have all been spotted tracking their stats with the device on their wrist or tucked under a sweatband.