Line calls in tennis are always a hot topic, but lately, things have gotten even spicier. To use Hawkeye or not? That’s the question. Aryna Sabalenka recently found herself right in the middle of it at the Stuttgart Open. During her quarterfinal clash against Elise Mertens at the Porsche Tennis Grand Prix, Sabalenka wasn’t happy with a key call. The line umpire made the decision, but the World No. 1 wasn’t convinced. She called the chair umpire down to have a look at the mark. However, the original call stood. Clearly frustrated, Sabalenka took a picture of the line mark herself to capture what she believed was a mistake. But the Belarusian isn’t the only one feeling the heat. Alexander Zverev had a similar experience with the Hawkeye. And a WTA pro has raised her voice against the system now.

During his match against Alejandro Davidovich Fokina, Zverev disagreed when the electronic system ruled one of his opponent’s balls in. The German, who wasn’t buying what the machine was selling, asked umpire Mohamed Lahyani to come down and check the mark. “The machine is not working. Look at this mark … Don’t overrule it, please come down,” he pleaded. But under the rules, the umpire couldn’t leave his chair to check. The television replay later showed the ball just barely catching the sideline. Not satisfied, Zverev took matters into his own hands, literally. He grabbed his phone, snapped a photo of the mark, and ended up delaying Davidovich Fokina’s serve. That move earned him a code violation warning for unsportsmanlike conduct. Even after winning the match, Zverev wasn’t done. He posted the picture on social media with the caption, “Interesting call,” and mentioned he plans to talk to ATP supervisors about his concerns with the technology.

Afterward, Croatian tennis star Donna Vekic also jumped into the debate. She posted her thoughts on X, saying, “So crazy that umpires are not able to overrule this! Insanity.” Her words echoed what many players and fans are feeling—that something just isn’t sitting right with the current system.

For context, in the past, umpires would come down from their chairs on clay courts and inspect the ball marks themselves. They would make the final call after checking it in person. Now, with Hawk-Eye Live fully in use across ATP events—including on clay—the human touch has been replaced by a machine that isn’t 100% perfect. There’s a known margin of error built into the system, but the sport is still adjusting to how it all plays out in real-time.

It’s not just Zverev and Sabalenka making noise. Germany’s Eva Lys and Belarus’s Victoria Azarenka have also taken photos of questionable marks during the Madrid Open. Frenchman Arthur Fils, after disagreeing with a few calls in his match against Francisco Comesana, made it clear he’s not a fan of the fully automated line calls either. He even called for a return to the days of human line judges.

While the debate rages on, Zverev is doing his best to stay focused on the court.

Alexander Zverev is on a winning streak at the Madrid Open

After a rough patch following his Australian Open final loss to Jannik Sinner, Alexander Zverev is finding his groove again. The German had a real shot at becoming World No. 1 during Sinner’s time off, but that dream slipped away after a slow couple of months. Between the Slam and the ATP 500 event in Munich, he won just six matches and lost six.

However, things are starting to turn around. The 28-year-old picked up his third title in Munich just last week, finally putting together a strong run. That title win has kickstarted a seven-match winning streak for Zverev now, his longest since a similar stretch between this year’s United Cup and the Australian Open.

Now, heading into the fourth round at the Madrid Open, Sascha has his sights set on making it eight straight. He’ll face either Francisco Cerundolo or Francisco Comesana next, as he hunts for a third title in Madrid.

All said and done, the clay-court season is heating up, and not just because of the tennis. As players battle it out on the court, another battle over line calls is just getting started. Should the tours rethink their reliance on technology? Share your thoughts in the comments below.