Three of the biggest names in tennis are in a bizarre controversy in Australia surrounding a popular wearable device.
Carlos Alcaraz was asked to remove a Whoop band hidden under his right wristband ahead of his fourth-round Australian Open match Sunday against Tommy Paul. The Whoop is a wearable device that tracks fitness and recovery metrics like heart rate and calories burned.
Alcaraz was not the only star who was told to remove the prohibited device, which the Australian Open says is banned at all Grand Slams—for now.
“The Australian Open is involved in ongoing discussions on how this situation could change,” tournament organizers said in a statement. (The ATP and WTA have let players wear the devices at tournaments in recent years, but the tours do not oversee the Grand Slams.)
Men’s world No. 2 Jannik Sinner was told to remove the tracker hidden underneath a wristband before his fourth-round match Sunday. Women’s world No. 1 Aryna Sabalenka was asked to remove the device ahead of her first-round match. (Sabalenka has an endorsement deal with Whoop.)
“Some wearables provide athletes with an indication of internal load (measures like heart rate), which can give them a 360-degree view of the work they’re doing and how their bodies respond,” Tennis Australia said in a statement about the controversy.
The federation added that it also gives information to players. “In terms of other data provided to athletes and their teams at the AO, players can monitor key external load measures such as distance covered, changes of direction, high acceleration events and speed/spin of shots via Bolt 6,” the Tennis Australia statement said.
Sinner said after the match that the data provided by the Whoop band helps provide important health data to players and their coaches. He said that there is a vest that players are permitted to wear that also tracks similar data, but he called it “uncomfortable.”
“There is certain data which we would like to track a little bit on court. It’s not for life, but more about what we can see after the match,” Sinner said. “Rules are rules and I understand and I won’t use it again.”
Sinner was hit with a three-month ban last year after he tested positive for clostebol, a banned substance.
The Whoop band is listed among the approved Player Analysis Technology products by the International Tennis Federation, tennis’s governing body. Tennis professionals are permitted to wear Whoop bands and other similar wearables on the ATP and WTA tours. Whoop was named the official wearable partner of the WTA in 2021, while the ATP allowed players to use wearable devices in July 2024.
The Slams operate independently from the ITF, WTA, and ATP. The USTA, which puts on the US Open, did not immediately comment. Spokespeople for the French Open and Wimbledon did not immediately respond to a request for comment.
“WHOOP believes athletes have a fundamental right to understand their own performance and health – including during competition at events like the Australian Open,” the company said in a statement to FOS. “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.”
The company also said on social media that taking away the players’ devices was “like asking athletes to play blind.”
Whoop has been used by professionals in other sports, most famously in golf.
The PGA Tour has shown the heart rates of players like Rory McIlroy, a Whoop investor, in the middle of the hole through information from the band. Women’s golf star Nelly Korda is also a Whoop endorser who wears the band at LPGA events.
