US Open Line-Call Error: Who Answers When the Machine Is Wrong?

The 2026 US Open's first line-calling controversy was not only a machine error. It was also a failure of the fallback. When the ELC Live system wrongly called Anna Kalinskaya's forehand out, the USTA later admitted that officials skipped the video review that should have caught it. The lesson for any sport automating its officiating: the system is only as trustworthy as the human protocol that takes over when it breaks.

Tennis has spent five years removing people from the lines. The US Open put Hawk-Eye Live on every competition court in 2021, and most line judges were gone by 2022. The pitch was that cameras are more accurate than people, and mostly they are. But the Kalinskaya point shows what happens once the people are gone: when the machine is wrong, the chair umpire is the only human left, and the process has to be airtight. On Court 5 it wasn't.

What happened in the Kalinskaya vs. Blinkova match?

On August 31, 2026, in the first round, No. 21 seed Anna Kalinskaya led fellow Russian Anna Blinkova 6-4, 2-2 and was serving at 40-15 on Court 5. After a short rally, Kalinskaya hit a crosscourt forehand that, according to The Athletic's report, bounced comfortably inside the singles sideline. The electronic system called it out.

Kalinskaya asked for a replay. When the replay came up, it showed a different point, a serve that had nothing to do with the shot in question. She protested to the chair umpire, telling them "You are here to watch!" and asking, "Why would I listen to this crazy call?" She also asked for the tournament supervisor. Several outlets, including Just Women's Sports and EssentiallySports, reported that the umpire refused. The call stood, and Kalinskaya lost that service game.

She still won 6-4, 6-3, so the result didn't change. That is the only reason this is a footnote rather than a scandal. In a tight third set or a tiebreak, the same failure decides a match.

What did the USTA admit?

The USTA did not blame the player or call the ball close. A USTA spokesperson gave The Athletic this statement, which Pro Football Network (syndicated on Yahoo Sports) and EssentiallySports also carried:

"At 40-15 in the fifth game of the second set, a malfunction with the ELC Live system caused a shot hit by Kalinskaya to be inaccurately called out. At this point, complete protocols were not followed by the officials involved in the match, which led to video review not being utilized. In this case, video review should have been applicable."

The statement admits two separate failures:

1. A technical failure. The ELC Live system produced a wrong call, and the replay feed showed the wrong point.
2. A procedural failure. A backup existed, and the officials didn't use it. According to The Athletic, 2026 is the first year video review is available on every US Open court, so the tool was there.

The second failure is the more important one. Sensors misfire, camera feeds drop, and operators make mistakes. A mature officiating system assumes that will happen and makes the recovery path automatic. Here, recovery depended on one official, under pressure, recognizing an unusual situation and invoking a protocol that was only recently extended to that court. The official didn't, and the player's request for a supervisor, the next safeguard, was turned down.

Who is accountable when there are no line judges?

Before automation, blame was easy to assign. A line judge called it, the chair could overrule, and players could see who got it wrong. Automated officiating splits that chain across several parties, and it is worth naming each of them:

Layer	Who owns it	What failed on Court 5
Ball tracking and the call	The ELC system and its operators (the US Open has used Hawk-Eye Live, from a Sony company, on all courts since 2021)	Called a ball out that was in, per the USTA
Replay display	The same system's replay feed	Showed footage from a different point
Chair umpire	USTA officiating staff	Did not start the video review the USTA says applied
Escalation	Tournament supervisor	Never reached; the player's request was refused, per multiple reports
Rules and protocol	The USTA as tournament operator	Protocol existed but wasn't followed, per the USTA's own statement

The honest answer is that the tournament operator carries the accountability, and the USTA effectively accepted that by publicly naming both failures. That matters. Governing bodies usually defend the technology by default, and tennis has sometimes done so. The USTA's statement takes the stronger position: the system can be wrong, and when it is, the officials are expected to catch it.

For players, though, an apology after the match fixes nothing. The point is gone. That is why the fail-safe design matters more than the accuracy rate.

Has electronic line calling failed like this before?

Yes, and the pattern is consistent: the failures come from how people operate and supervise the system, not from the camera tracking itself.

• US Open 2020: Hawk-Eye North America managing director James Japhet told ESPN that in the first week of the 2020 US Open, 14 of 225,000 calls were wrong, "and those were the result of human error by operators."
• US Open 2023: Video review debuted as a Grand Slam first. In its very first use, during Andy Murray vs. Corentin Moutet on August 29, the chair umpire's tablet malfunctioned. Tennis.com reported the USTA's rule: "If the video is not available on the chair umpire's tablet, the original call on the court stands." Moutet lost his challenge opportunity.
• US Open 2024: On September 2, a fire alarm evacuated the building that houses the line-calling system. According to ESPN, play stopped on all courts, including Arthur Ashe and Louis Armstrong, for six minutes.
• Wimbledon 2025: In a fourth-round Centre Court match between Anastasia Pavlyuchenkova and Sonay Kartal, the system was switched off by mistake on part of the server's side of the court for one game. A clearly long ball went uncalled, and the chair umpire replayed the point. According to the Associated Press report carried by PBS, Wimbledon then "removed the ability for Hawk-Eye operators to manually deactivate the ball tracking." Days later, in the Taylor Fritz vs. Karen Khachanov quarterfinal, NBC News reported the system mistook a rally shot for a serve and called a fault, and the point was replayed.

All England Club chief executive Sally Bolton put it plainly in 2025: the technology is "not an artificial intelligence system," and it "requires a human element to ensure that the system is functional." The Kalinskaya point shows where that human element sits after the line judges leave. It sits in the operations bunker and the chair, and both have to be trained for the failure case, not just the normal one.

What fail-safes does automated officiating need?

Every major sport now faces this design problem. Football's semi-automated offside and baseball's robot umpire both rely on the same bargain: trade human judgment for machine precision, then keep a human escape hatch. We've covered how FIFA built its semi-automated offside stack and how MLB's ABS challenge system keeps a human appeal in the loop. Based on the Court 5 failure and the incidents above, a credible fail-safe design for tennis needs five things:

1. Automatic triggers, not discretionary ones. If the replay feed shows the wrong point, or the system flags low confidence, video review should start by default. The USTA's own statement says review "should have been applicable." It shouldn't depend on an umpire noticing that.
2. A guaranteed player escalation path. A request for the supervisor after a documented system malfunction should never be refused. It costs a minute and preserves trust.
3. Safe failure states. Wimbledon's fix, removing operators' ability to switch off tracking, is the right idea: design out the error rather than retrain around it. The 2023 tablet rule, where the on-court call stands if video is unavailable, is the opposite: it defaults to the possibly wrong outcome.
4. Transparent replays. Players and fans should see the same evidence the officials see, in time to matter. A replay of the wrong point is worse than no replay, because it looks like confirmation.
5. Published incident data. The USTA and Hawk-Eye have cited error rates for years. Publishing a per-tournament log of malfunctions, overturned calls and protocol lapses would let players judge the system on evidence rather than on viral clips.

None of these require new camera technology. They are operations and governance fixes, which is also why they tend to get skipped.

What are the new net-post lights at the 2026 US Open?

The one visible officiating change fans noticed this year is small and sensible. According to AOL and EssentiallySports, the US Open added red lights to the net posts that flash as soon as the electronic system calls a ball out. The same approach was used at the United Cup and the Australian Open earlier in 2026. Tennis journalist Ben Rothenberg welcomed the change on X, calling the lights "sorely needed year-round in this era of electronic line calling ambiguity."

The lights solve a real problem: the automated "out" call is an audio announcement that can be hard to hear in a loud stadium. They do not solve the Kalinskaya problem. A light flashing on a wrong call is still a wrong call, only more visible. Clearer output is good, but the weak point this year was verification.

How does IBM's AI fit into the US Open tech stack?

IBM's work at the tournament is on the fan side, not officiating, and it's worth keeping the two separate. On August 24, 2026, IBM and the USTA, partners since 1992, announced new AI features for the 2026 US Open:

• Serve Quality: According to IBM, it uses limb-tracking technology "developed with IBM Bob" to analyze serve mechanics across 21 data points on the body and racquet, tracked 50 times per second, generating roughly 1.2 billion data points over the tournament.
• Key Moments: Builds on the existing Likelihood to Win feature to explain why momentum shifted, not just who is ahead.
• Match Chat: A conversational companion, powered by IBM's watsonx Orchestrate, that lets fans ask questions in their own words during a match and get conversational answers.
• Live Updates homepage: A personalized feed on USOpen.org and the US Open app that prioritizes a fan's favorite players.

The contrast is useful. Fan-facing AI can be approximately right and still be valuable: a serve score that's a little off costs nobody a game. Officiating technology has no such tolerance. The US Open is investing in both at once, and the Kalinskaya point is a reminder that the stakes for each are very different. For more on how ball-tracking vendors compete for this business, see our breakdown of the Hawk-Eye, TrackMan and Sportvision ball-tracking market.

What should operators and fans take from this?

Automated officiating has won the accuracy argument, and tennis is not going back. Sean Cary, the USTA's managing director of competition operations, told ESPN in 2022 that "it would be very hard for us to go backwards." The next argument is about recovery: what the system does in the rare moment it is wrong. The USTA's candid statement is a good start. What would show real progress by the 2027 season is a protocol where review is triggered automatically, player escalation is guaranteed, and malfunction data is published. For anyone building automated decision systems outside sport, the takeaway is the same: design the failure path first, because that is the part people will judge you on.

Frequently Asked Questions

What was the US Open electronic line-calling error in 2026?

In a first-round match on Court 5 on August 31, 2026, the ELC Live system wrongly called Anna Kalinskaya's crosscourt forehand out at 6-4, 2-2, 40-15 against Anna Blinkova. The replay showed a different point. The USTA later confirmed the malfunction and said officials failed to use the video review that applied. Kalinskaya still won 6-4, 6-3.

Did the USTA apologize for the Kalinskaya line call?

The USTA gave The Athletic a statement acknowledging that "a malfunction with the ELC Live system" caused the wrong call and that "complete protocols were not followed" by the officials, so video review wasn't used. It said review "should have been applicable." The on-court result was not changed.

Does the US Open still use line judges?

Mostly no. The US Open put Hawk-Eye Live electronic line calling on all competition courts in 2021, and most line-judge roles were eliminated by 2022, according to ESPN. Each match has a chair umpire who calls the score, handles video review and can step in when the system malfunctions.

What do the red lights on the net posts mean?

At the 2026 US Open, red lights on the net posts flash when the electronic line-calling system calls a ball out, according to AOL and EssentiallySports. They make the recorded "out" call visible in loud stadiums. The same idea was used at the United Cup and Australian Open earlier in 2026.

Is IBM's AI used for line calls at the US Open?

No. IBM's 2026 US Open features, including Serve Quality, Key Moments and Match Chat powered by watsonx Orchestrate, are fan-facing digital experiences on USOpen.org and the US Open app. Line calls come from the electronic line-calling system, which the US Open has run on all courts since 2021.