New York - Andy Murray refused to blame his US Open defeat to Kei Nishikori on a series of bizarre phantom gong sounds emanating from a malfunctioning sound system on Arthur Ashe Court.
The 2012 US Open winner, and reigning Wimbledon and Olympic champion, slumped to a 1-6, 6-4, 4-6, 6-1, 7-5 loss to the Japanese sixth seed in a thrilling four-hour clash on Wednesday.
World No 2 Murray looked to be in control at two sets to one ahead and had carved out a break point in the third game of the fourth when a loud sound burst out.
It thudded around the stadium and echoed eerily beneath the roof which had been closed due to rain midway through the second set.
Umpire Marija Cicak ordered the point to be replayed much to the irritation of Murray who lost his composure and the next seven games.
Murray was so agitated that he summoned tournament referee Wayne McKewen to register his complaint.
"Wayne told me that it happened four times during the match that the speakers had gone off like that," said Murray who lost to Nishikori for only the second time in nine matches.
"I had only heard it one time before, which was on set point in the second set. That was it."
Murray admitted that he briefly lost his composure which opened the door for 2014 runner-up Nishikori who has now beaten top 10 players five times at the US Open.
"Definitely I would say to 4-1 I didn't play a good game after I got out of the change of ends, and then he held pretty comfortably the next game," said the Briton.
"But after that, I don't think so. I lost my serve a couple of times from positions when I was up in the game."
The quarter-final featured 17 breaks of serve and five in the last set where Nishikori had led 4-2 at one stage.
Murray then won three games on the spin before Nishikori held his nerve to claim a famous win on the back of a blistering 48 winners.
US Open organisers admitted that the sound system was at fault but to replace it would have meant delaying the match.
A women's fourth round match on Monday suffered similar problems as Ana Konjuh was serving for the match against Agnieszka Radwanska.
Konjuh was clearly startled by the bang but went on to serve out the match.
"One of the three digital audio sound processors in Arthur Ashe Stadium malfunctioned early in the fourth set of the Kei Nishikori - Andy Murray match," said a USTA statement.
"The malfunctioning unit is located at the court level....it could not be taken off-line without interrupting play."
The system was due to be fixed before the night session on Wednesday when Serena Williams faced Simona Halep and Juan Martin del Potro tackled Stan Wawrinka.
Meanwhile, Murray said he was not too despondent over his earlier than planned exit from the US Open, where he has yet to get past the quarter-finals in the four years since he ended Britain's 76-year wait for a Grand Slam men's champion.
He had been on a 26-1 run this summer, winning Queen's, Wimbledon and the Olympic title.
Defeat, however, ended his bid to become just the fourth man to make the finals of all four majors in the same season.
"I tried my best. I fought as hard as I could with what I had today. I didn't let anyone down. Certainly not myself," said Murray.
"I pushed myself as hard as I could over the last few months, and I'm very proud of how I have done.
"If someone had offered me the summer that I have had before Wimbledon, I probably would have signed for that."