Ana Ivanovic crashed out of the Australian Open after her coach, Andy Murray's father-in-law Nigel Sears, collapsed in Melbourne and her match against Madison Keys was delayed for almost an hour.
Sears was taken to hospital after falling in the stands on Rod Laver Arena during a match.
Tournament organisers said Sears was "breathing, conscious and talking" and being examined by a cardiologist at a nearby hospital after being carried out of the showcourt on a stretcher.
Sears had been watching Ivanovic's third round clash against American Madison Keys when he was taken ill and the match was halted for nearly an hour after the incident.
The Serb was leading 1-0 in the second set after taking the first 6-4 when play was suspended but eventually went down 4-6 6-4 6-4 to exit the tournament.
Organisers said the players had been given the opportunity to consult with their teams before play was resumed.
Murray, oblivious to the development, continued to play his third round match against Portugal's Joao Sousa on Margaret Court Arena, winning 6-2 3-6 6-2 6-2.
He was ushered away after the victory without the usual courtside interview.
Sears is the father of Murray's wife Kim, who is expecting their first child in mid-February and has not travelled to Melbourne.
Television microphones picked up Ivanovic telling chair umpire Felix Torralba that she thought the person being treated was her coach before play was eventually suspended.
Ivanovic still appeared distressed when returning to court almost an hour later but tournament organisers said a discussion had taken place with both players before play resumed.
The 58-year-old Sears had previously coached Slovakia's Daniela Hantuchova, leading her to a top-10 ranking. He joined Ivanovic in June 2011 after almost five years with the Lawn Tennis Association and Britain's Fed Cup team.
They parted company after Wimbledon in 2013 but he rejoined her team last year.
It is the second time this tournament that one of Ivanovic's matches had been suspended after her second round match against Anastasija Sevastova was held up for 26 minutes when a woman fell in the stands at the same showcourt.
Johanna Konta has matched her best ever performance at a grand slam as the British number one dispatched Denisa Allertova to reach the last 16.
It took Konta 14 attempts to go past the fourth round at a major tournament but after her success at last year's US Open, she has now managed it twice in a row after easing past Allertova 6-2 6-2.
The world number 47, who is set to climb into the top 40, will now play Russia's 21st seed Ekaterina Makarova for a place in the quarter-finals.
Makarova feels at home in Melbourne, having reached the semi-finals here 12 months ago and the quarter-finals in both 2012 and 2013, but Konta beat her in Eastbourne last year and will fancy another upset.
Allertova was certainly no match for her resurgent opponent in Hisense Arena and the fact this dominant victory came just eight months after Konta lost the pair's last meeting at the French Open, is a mark of how far the Briton has risen.
"It was not easy out here today, she's an incredibly tough opponent"
Her opponent has also been in good form but Allertova was wearing heavy strapping around her left thigh and, whether fully fit or not, never really gained a foothold in the contest.
Konta was too strong at the back, where her rasping forehand dictated the exchanges, and ruthless on serve, serving five aces and not offering a single break point during the entire match.
She broke Allertova in the very first game and then again in the seventh, before clinching the first set with an ace in 29 minutes.
The second set followed the same pattern as Konta raced ahead 2-0 and, unlike in her opening two rounds, there was no late wobble as she sealed victory with a forehand pass in just over an hour.
"It was not easy out here today, she's an incredibly tough opponent," Konta said.
"I had a tough match against her at the French Open so I knew I had to run every ball down and fight for every point. It definitely wasn't easy."
Belarus tennis ace Victoria Azarenka (above) was more refined than former Australian cricketer Keith Miller when it came to dismissing concerns about pressure in sport, but the sentiment was similar.
Miller, a Royal Australian Air Force pilot during World War Two, famously quipped that pressure was being chased by a German fighter plane not playing Test cricket.
On Saturday, after reaching the fourth round in the shadow of the cricket ground where Miller once plied his trade, twice champion Azarenka was quick to dismiss any concerns she was feeling the weight of expectation.
"Pressure is if you don't win some tournaments you have absolutely no opportunity to go to any other," she said after her confident 6-1 6-1 win over Japanese teenager Naomi Osaka (below).
"If you're not the best you don't get sponsored.
"I had no money. I didn't get to eat. So that was pressure to survive," she said of her days in the junior ranks.
"So pressure right now is go out there and face a big opponent? Okay.
"But when you're hungry and you've got to go play and you have absolutely nothing, that's big pressure."
Azarenka will now play Czech Barbora Strycova for a place in the quarter-finals, while also in the bottom half of the draw is Chinese qualifier Shuai Zhang, who extended her fairytale run in Melbourne.
Zhang had lost in 14 consecutive grand slam first rounds coming into the tournament but now finds herself on the brink of the last eight after following up wins over Simona Halep and Alize Cornet with a 6-1 6-3 victory against American Varvara Lepchenko.
"Do I believe I can win the tournament? Before, no. But today maybe yes," said Zhang, who now plays Madison Keys.
Third seed Garbine Muguruza was dumped out by Strycova, while seventh seed Angelique Kerber and Annika Beck make up an all-German fourth round clash.
