Damir Džumhur and Matteo Arnaldi’s quarterfinal clash at the Croatian Open in Umag descended into controversy after a wild electronic line-calling decision went the Italian’s way. As the visible ball mark supported Džumhur’s furious protests, former Australian player John Millman and several others from the tennis community weighed in on the incident.
How the Tennis World Reacted to Damir Džumhur’s Line-Calling Drama
Džumhur and Arnaldi were locked in a closely contested battle at the ATP 250 event when controversy erupted in the first-set tiebreak. With Džumhur leading 4-1 in the tiebreak, Arnaldi’s serve was ruled in by the electronic line-calling system, which allowed the Italian to narrow the gap to 4-2.
The Bosnian immediately protested the call and angrily confronted the chair umpire, who made it clear that he couldn’t overturn the decision. As the ball mark showed that the serve had landed well out, Džumhur then called the videographers over to document the mark.
“How can you tell me? You are looking in my eyes and lying to me. You know that this ball is out. Can you tell me if this ball is out? If you are an honest person, you are going to answer. Is this ball in or out? Be honest once in your life!” Džumhur said.
As a clip of the incident circulated online, tennis journalist José Morgado expressed his disbelief over what had unfolded.
“Still cannot believe this happened. Tennis can’t be this unserious…,” Morgado wrote.
Still cannot believe this happened.
Tennis can’t be this unserious… pic.twitter.com/Hq7UOyjHVP
— José Morgado (@josemorgado) July 17, 2026
John Millman entered the discourse, criticizing the reliance on the electronic line-calling system and arguing that the erroneous call should have been overturned by the chair umpire.
“How can common sense from the chair umpire not come into play here? It’s clearly out, the automated line calling got it wrong. You can’t blindly accept a computer,” Millman commented.
Although journalist Tom Tebbutt empathized with the chair umpire, he echoed Millman’s stance that the Hawk-Eye system is not infallible.
“It’s certainly not game, set and match for ELC. Hard to believe it is not fallible. Probably less fallible than lines-persons, but still imperfect. You had to feel for umpire John Blom. But it still would have been nice to see him overrule the machine. A good clay court can be the ultimate arbiter – better than hard or grass,” Tebbutt posted.
Tennis reporter Marco Mazzoni also denounced the incident as “ridiculous,” suggesting that either the tour should bring back human line judges or allow supervisors to intervene when such “blatant” errors occur.
“This ball (an Arnaldi serve) at Umag was called good by the electronic system. Dzumhur, furious, even got a Warning. The chair umpire, at Damir’s request, said, “I can’t say if the ball is out.” Frankly, we’re in the ridiculous. RIDICULOUS. On clay courts, it’s necessary to go back to line judges, or the supervisor should step in with such blatant errors. We’re in a comedy,” Mazzoni wrote in Italian.
Despite the controversy, Damir Džumhur went on to win the first set and eventually claimed a hard-fought 7-6(5), 6-7(4), 7-6(4) victory over Matteo Arnaldi after a 3-hour, 42-minute battle. The Bosnian then triumphed over Alex Molčan 3-6, 6-4, 6-3 to book his spot in the Croatian Open final, where he will face Daniel Mérida.
