Wimbledon organisers have apologised after the electronic line-calling system on Centre Court was turned off in error and missed three calls in one game.

Anastasia Pavlyuchenkova said a game was 'stolen' from her after there was no 'out' call when a Sonay Kartal backhand went long in the first set of their fourth-round match.

The Russian stopped after seeing the ball go long, and chair umpire Nico Helwerth halted play.

The All England Club initially said the system was "deactivated on the point in question" because of "operator error".

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".

During that time, three calls on the affected side of the court were not picked up.

Helwerth, who did not know the system had been turned off, called two of them himself before the incident highlighted by Pavlyuchenkova.

"We have apologised to the players involved," said a spokesperson for the All England Club.

"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."

Had the ball been called out, Pavlyuchenkova would have won the point and taken the game.

After stopping play, Helwerth told the crowd: "We're just going to check if the system was up and running, because there was no audio call."

After a telephone call, he announced the electronic system "was unfortunately unable to track the last point" and ordered it to be replayed.

Kartal won it and went on to break for a 5-4 lead.

The rulebook states that if the electronic line-calling system fails to make a call, "the call shall be made by the chair umpire".

It adds: "If the chair umpire is unable to determine if the ball was in or out, then the point shall be replayed. This protocol applies only to point-ending shots or in the case when a player stops play."

The fact Pavlyuchenkova went on to win the match meant the malfunction was not as costly as it could have been, although she still questioned why the umpire did not call it out.

"That's why he's there," she said. "He also saw it out, he told me after the match.

"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."

'You took the game away from me'

Pavlyuchenkova's frustration had been clear when she returned to her chair at the end of the game in question.

She told the umpire: "You took the game away from me... they stole the game from me. They stole it."

Automated line-calling has been introduced at Wimbledon for the first time this year.

It has been under scrutiny this week, with a number of players saying they do not trust it.

Britain's Emma Raducanu has been one of those to voice concerns, saying some of the calls had been "dodgy", while former Olympic champion Belinda Bencic said the technology was a topic of discussion among players in the locker room.

Bencic said she was usually a fan of the technology, but "it is not correct" at this tournament.

Line judges have been replaced by technology at many top-level tournaments, including the US Open and Australian Open.

Debbie Jevans - chair of the All England Club - said the technology had been brought in because "the players wanted it" and some have backed the system, with former world number one Iga Swiatek saying she has had doubts but "has to trust" the calls.

'Let's just play without umpires'

When there were line judges, players could challenge calls by using an electronic review. There are no challenges under the current system, and video replays are not used.

Former Wimbledon champion Pat Cash, speaking on BBC One's coverage, said it was "mind-boggling" the chair umpire did not call the ball out himself.

"The chair umpire is there for that reason," he said.

"It was clearly out so I don't understand why he couldn't just call it out, call the game and sort it out at the change of ends.

"So what if the machine didn't say it? It was so far out and right in front of his face."

Pavlyuchenkova suggested tennis should use video checks like football does "so that we can review the point".

"On such a big event, I think it is necessary, since this isn't the first time this has happened," she told BBC Sport.

She said umpires were there to make big decisions, otherwise they could "just play without them", adding: "I think the chair umpire should be able to take initiatives.

"That's what he is there for, and that's why he is sitting in that chair; otherwise, I think we could have also had a match without a chair umpire."