Following in the footsteps of the U.S. Open and the Australian Open, Wimbledon finally did away with human line judges in favor of Hawk-Eye technology at this year’s Championships.

All 18 courts have incorporated the system, which uses multiple high‑speed cameras and real‑time computer vision algorithms, with loudspeakers emitting an audible “out” to confirm a missed shot.

A week into this year’s competition, the technology appeared to be working well. But then, during a high-profile match on Centre Court on Sunday involving Brit Sonay Kartal and Russian Anastasia Pavlyuchenkova, the system seemed to go a bit quiet, with the umpire having to confirm a couple of widely missed shots as out.

But then, a short while later, on a game point for Pavlyuchenkova toward the end of the first set, Hawk-Eye failed to call a ball hit by Kartal that landed a foot past the baseline, with Pavlyuchenkova half-heartedly keeping it in play. Despite having clearly won the point — and therefore the game — Pavlyuchenkova was told to replay it. She lost the point and went on to lose the game.

It was a confusing mess, with Pavlyuchenkova complaining during the changeover that “they stole the game from me.”

Fortunately for the Russian, she managed to retain a cool head and went on to win the match. But it could have turned out very differently.

The All England Club, which runs Wimbledon, said at first that the system was “deactivated on the point in question” because of “operator error,” according toa BBC report.

A spokesperson said later on Sunday that, after further investigation, it was found the technology was “deactivated in error on part of the server’s side of the court for one game.”

The spokesperson added: “We have apologized to the players involved. We continue to have full confidence in the accuracy of the ball-tracking technology. In this instance, there was a human error and as a consequence we have fully reviewed our processes and made the appropriate changes.”

Having overruled some earlier calls, it’s not clear why the umpire failed to do the same for this shot, which was clearly out. The rulebook states that the umpire has the power to make a call if Hawk-Eye fails to do so.

“He also saw it out, he told me after the match,” Pavlyuchenkova said in a post-match press conference. “I thought he would do that, but he didn’t. Instead they just said replay. I don’t know if it’s something to do [with Kartal being] local. I think it’s also difficult for him. He probably was scared to take such a big decision.”

Sunday’s Hawk-Eye hiccup demonstrates that even automated line-calling systems are not infallible, a reality that, going forward, will put even greater pressure on the only human left officiating the match — the umpire. It’ll be interesting to see how Pavlyuchenkova’s experience affects next week’s Wimbledon matches, with players perhaps more likely to look the umpire’s way if they’re expecting a shout from Hawk-Eye that doesn’t come.