How did an ATP Challenger in Germany make history with Electronic Line Calling?

As fans tune in to matches from Roland Garros, one detail stands out: the tournament remains the only Grand Slam still using traditional on-court line judges. Elsewhere, Electronic Live Calling has become the norm - especially on hard and grass courts. Even on clay, where ball marks are visible to the naked eye, the ATP Tour has embraced machine-based line calls this season.

While clay courts may give the illusion of clear ball marks, these often don't reflect the actual point of contact. The reasons are numerous: players’ footwork can overlap markings, multiple rallies in the same zone can mix up impressions, and environmental factors like wind or dry soil can distort the shape or size of a ball mark. Moreover, clay court lines are slightly elevated. If a ball clips the line, parts of its mark may be erased, making it nearly impossible to determine whether the ball was in or out.

A world-first on clay in Heilbronn

The world premiere of Electronic Live Calling on clay took place exactly one year ago at the Neckarcup ATP Challenger in Heilbronn. The Barcelona-based company FOXTENN provided the technology, which was implemented across all courts for the entire week at Tennis Club Trappensee.

At that time, FOXTENN was the only line-calling system on the market that relied 100 per cent on real images. And that, as founder and CEO Javier Simón explained, is its major advantage:

“FOXTENN is the only system that is based 100 percent on real recorded images, while other systems work with estimations, such as the ball’s trajectory, and therefore cannot guarantee complete accuracy.”

During the 2024 edition of the Neckarcup, FOXTENN was equipped with state-of-the-art technology: 42 high-speed cameras and 10 laser scanners, capturing 3,000 images per second - far surpassing the 25 frames the human eye processes. This allowed for absolute precision in determining whether a ball hit or missed the line.

“We are very satisfied with how it's going. By now, we’ve completed around 50 matches and analyzed more than 10,000 situations where the ball landed directly on the line,” Simón reflected during the tournament.

Behind the scenes

In a separate room inside a nearby tennis hall, a team of about ten FOXTENN staff worked behind the scenes. Each court had three dedicated operators: one handling laser measurement, one for the cameras, and another serving as the interface between ATP officials and the chair umpires.

“If a player requests a review, communication has to be lightning fast,” Simón emphasized.

More than just close calls

FOXTENN’s capabilities extend beyond just line calls. The system provides detailed match analytics and statistics, invaluable for television broadcasts, ATP officials, and the players themselves. It’s not merely a decision aid—it’s a comprehensive data tool for the future of the sport.

Praise for the Neckarcup

According to Simón, the Neckarcup, a three-time winner of the ATP’s Best Challenger Tournament award, offered the perfect setting for this technological breakthrough:

“I’ve been to many Challenger events, but the Neckarcup is without doubt one of the best in the world. It’s professionally organized, yet has a very familial atmosphere.”

By debuting Electronic Live Calling on clay, the Neckarcup not only turned a new page in tennis innovation but also cemented its status as a trailblazer on the ATP Challenger Tour.