Electronic line calling on clay still confuses tennis players and fans. But is it the issue?

Welcome back to the Monday Tennis Briefing, where The Athletic will explain the stories behind the stories from the past week on court.

This week, electronic line calling once again caused chaos on clay, a strange Madrid Open provided winning memories, and the wearable-tech arms race evolved.

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Did arguments over electronic line calling actually represent a step forward?

The electronic line calling (ELC) system is the letter of the law across top-tier tennis these days, but that didn’t stop an old stalwart of clay-court season from cropping up at the Madrid Open: Players arguing with umpires over ball marks.

Alexander Zverev, Mirra Andreeva and Elena Rybakina all asked a chair umpire to come down and check a physical ball mark they believed to prove a shot landed out which the ELC system had called in.

Umpires declined to check the traces each time.

“This is a joke. The system is wrong. This is not a joke. There is no such mark which is shown on the TV,” Rybakina said, imploring umpire Julie Kjendlie to come down from her chair during her second-round match against Zheng Qinwen.

“That’s what I have to go with. Now that we have live ELC, that’s what we have to go with,” Kjendlie said.

Since ELC was widely adopted at clay events on the ATP and WTA Tours last year, players have been educated on the fact that ball marks on the surface can be deceiving. The tours collaborated on a video explaining the discrepancies between the system it uses and the ball marks on the surface, which have been reiterated in other communication channels.

Clay is affected by environmental conditions, as well as how much red brick-dust happens to be on a certain part of the court at a certain time, and those conditions change from point to point as players slide and move around the court. A ball that lands in can leave a mark outside of the line; a ball that lands out can leave a mark that appears as if it has caught.

It was Andreeva’s disagreement that was most illuminating. “I understand that you cannot overrule. But as players, what do we do?” she asked chair umpire Kader Nouni.

The players are still learning to trust the electronic system, after being told last year that the way they’ve been calling balls on clay their entire lives no longer applies. There is also the possibility that players know the system is correct but sometimes, in the heat of competition, feel that their best course of action is to start an argument with the umpire.

There are other things the sport could do, for fans, too. Broadcasters explain the system infrequently and commentators sometimes appear caught out during confrontations, while the top-down replays used during matches arguably make the situation worse. They reproduce the perspective of the confused player looking down at the court, not the system checking whether or not the ball has made contact with the line.

What instances like those involving Zverev, Andreeva and Rybakina in Madrid also prove is how counterproductive the upcoming French Open’s decision to eschew ELC and continue using the physical traces of the ball is.

The tours have asked players to shift their mindsets about ball marks on clay, while the French Open, the only Grand Slam that hasn’t adopted the electronic system, asks them to revert for a few weeks every year.

That’s not good for a system that requires some amount of buy-in on clay, and it complicates things for viewers. The French Open is muddy enough already without it.

— Ava Wallace

How did a funky tournament provide some winning memories?

For those sweating at the thought of a French Open this year without the Jannik Sinner-Carlos Alcaraz rivalry to ballast the men’s draw, the Madrid Open provided a delightful counterargument.

Between 23 withdrawals — including Alcaraz, who has announced his 2026 clay-court season is over due to a wrist injury — a viral stomach bug and a slew of early-round upsets of top players, this tournament should have been a mess.

But the tennis prevailed. When I think of this Madrid Open in the future, I’ll think of Hailey Baptiste, first executing, in a fourth-round win against Belinda Bencic, perhaps the most artful racket smash I’ve ever seen, then playing the match of her life to defeat Aryna Sabalenka in the quarterfinals.

Baptiste is no newbie on tour, but the first sustained look at her prowess on clay came during a tantalizing run to the fourth round at Roland Garros last year. She made good on that promise against world No. 1 Sabalenka in Madrid, unloading her abundant toolkit and playing the kind of courageous tennis that made it hard to stay seated on the couch while watching at home.

There was more from players ranked outside of the top 10: Frenchman Arthur Fils rattled off an impressive run to the semifinals, meaning the worst he’s done in his first four tournaments after returning from a stress fracture in his lower back is the last eight in Indian Wells.

Alexander Blockx, 21, started the tournament ranked No. 69, took out four seeded players with his brawny game and outlasted 19-year-olds Rafael Jódar and João Fonseca in the draw to be the last youngster standing before losing to Zverev in the semifinals.

World No. 23 Marta Kostyuk prevailed to win the biggest title of her career against Andreeva in a rare final between two players coached by women: Andreeva’s Conchita Martínez and Kostyuk’s Sandra Zaniewska.

It wasn’t the final match of the tournament, but Kostyuk pulling off a back handspring after winning the trophy summed up a Madrid Open which could have been a strange letdown: It was unexpected, and full of joy.

— Ava Wallace

What now for the wearables arms race in tennis?

A couple of weeks after the news that tennis players can use approved wearables at the three remaining Grand Slams of 2026 on a trial basis, the U.S. Open went a step further.

On Thursday, the United States Tennis Association (USTA) announced a five-year partnership with Oura, the company known for a ring that tracks metrics including sleep, heart rate and stress. A news release from the USTA said that Oura would become “an official sponsor and wearable fitness device partner of the U.S. Open, USTA and USTA Coaching”.

Oura rings will be available to every player in the U.S. Open main draws and be integrated across a number of USTA platforms, including coaching programs and internal leagues. Oura will also become a founding partner of the U.S. Open’s Player Performance Center — a new hub for players to assess their health and performance during the tournament, which is part of the $800 million renovation of its Arthur Ashe Stadium due to be completed in 2027.

At January’s Australian Open, Sabalenka, Alcaraz and Sinner were all asked to remove bracelets made by another wearable company, Whoop, ahead of matches. The bands, which track biometric data including heart-rate variability, skin temperature and blood oxygen, were not approved by the tournament, despite the men’s and women’s tours and the International Tennis Federation (ITF), whose rulebook the majors follow, permitting them.

The four Grand Slams can individually decide which wearables can and can’t be used, irrespective of the ITF’s list. Tennis Australia did not let players use the Whoop bands, which are on the ITF list; the U.S. Open has now approved these Oura rings, but they are not yet on the ITF list. Two people with knowledge of the approvals process, who were not authorized to speak publicly about it because it is confidential, said that Oura is in the process of obtaining ITF approval.

A more liberal approach to wearables will be well received by players after their criticism of the Australian Open’s approach in January. Sabalenka, who is a Whoop ambassador, argued that they should have access to their own health data.

“There is certain data that we would like to track a little bit on court. It’s not for the live thing,” Sinner said at the Australian Open, countering the idea that wearables offer a tactical advantage during play. “It’s more about what you can see after the match. This is data that we would like to use also in practice sessions.”

The NBA, NFL, MLB, WNBA and professional golf all permit wearable technology in some capacity. In tennis, the information provided by wearables is key for players, coaches and federations, including Britain’s Lawn Tennis Association, for managing performance aspects such as load management and injury prevention.

The USTA hopes the Oura rings will aid elements such as training and recovery. During the Australian Open, the Professional Tennis Players’ Association medical director, Dr. Robby Sikka, said that “other major sports leagues have already built thoughtful, evidence-based frameworks for wearable technology” in a text message.

“The NFL allows approved wearables and tracking, the NBA operates a formal wearables committee with full player access to their data, MLB rigorously vets devices, and global soccer leagues have multiple approved systems in place. Tennis should meet that same standard.”

The U.S. Open’s Oura partnership, and the more laissez-faire approach to wearables at the French Open and Wimbledon this year, suggests tennis is starting to catch up.

— Charlie Eccleshare

Shot of the week

Any one of Baptiste’s best strokes during her win over Sabalenka could have made the cut, but this drop shot/lob combination to save match point was particularly special:

🏆 The winners of the week

🎾 ATP: 

🏆 Jannik Sinner (1) def. Alexander Zverev (2) 6-1, 6-2 to win the Madrid Open (1,000) in Madrid. It is his fifth consecutive ATP Masters 1000 title.

🎾 WTA:

🏆 Marta Kostyuk (26) def. Mirra Andreeva (9) 6-3, 7-5 to win the Madrid Open (1,000) in Madrid. It is her first WTA 1000 title.

📈📉 On the rise / Down the line

📈 Marta Kostyuk moves up eight places from No. 23 to No. 15 after her Madrid Open win.

📈 Alexander Blockx ascends 33 spots from No. 69 to No. 36 after his run to the Madrid Open semifinals.

📈 Hailey Baptiste rises seven spots from No. 32 to No. 25, a new career high.

📈 Arthur Fils rises eight spots from No. 25 to No. 17.

📉 Jack Draper falls 22 places from No. 28 to No. 50.

📉 Donna Vekić drops 23 places from No. 66 to No. 89.

📉 Casper Ruud leaves the top 20, tumbling 10 spots from No. 15 to No. 25.

📉 Emma Navarro leaves the top 30, moving down six spots from No. 28 to No. 34.

📅 Coming up

🎾 ATP 

📍Rome: Italian Open (1,000) featuring Jannik Sinner, Alexander Zverev, João Fonseca, Rafael Jódar.

📺 UK: Sky Sports; U.S.: Tennis Channel 💻 Tennis TV

🎾 WTA

📍Rome: Italian Open (1,000) featuring Aryna Sabalenka, Elena Rybakina, Iga Świątek, Coco Gauff.

📺 UK: Sky Sports; U.S.: Tennis Channel

Tell us what you noticed this week in the comments below as the men’s and women’s tours continue.

This article originally appeared in The Athletic.

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