(Sports) Medical emergency on night 6 of Australian Open hits close to home for Ivanovic, Murray

Night six of the Australian Open has been overshadowed by another medical emergency in the stands, this time indirectly involving some of the sport's biggest names.

The coach of 20th-seed Ana Ivanovic, Nigel Sears, fell to the floor while watching his charger's third-round match against American Madison Keys on Rod Laver Arena (RLA).

Sears, who is the father-in-law of two-time Grand Slam champion Andy Murray, was rushed to hospital after medical personnel reportedly administered CPR to the 58-year-old.

Play was stopped for almost an hour while the man, who tournament organizers failed to identify, was treated.

"The match was suspended and the players updated on his condition. The players had the opportunity to consult with their teams and then went back on court," a statement from the Australian Open read on Saturday night.

It's the third time on-site medics have been called in to treat a stricken spectator at this year's tournament, with two separate incidents occurring earlier this week.

Upon resumption of play at 1-0 in the second set, Ivanovic looked unperturbed by events transpiring off the court as she raced to within two games a straight-sets win.

But Keys brought her A-game in the back-end of the set, holding off six break points at 5-4 to level terms at a set apiece.

Again the French Open-winner raced ahead in the third, but Keys rallied to win 4-6, 6-4, 6-4 in two hours and 25 minutes.

Both Ivanovic and Keys were not available for post-match press conferences, instead releasing prepared remarks to the media with no mention of the incident.

Over on Margaret Court Arena (MCA), Murray remained blissfully unaware of the drama unfolding across on RLA, and didn't panic after he dropped his first set at this year's tournament.

Joao Sousa sprung a surprise attack on the 28-year-old Scot, ramping up his game to steal the second set in 49 minutes.

But Murray, a four-time runner-up at this event, recovered to produce a 6-2, 3-6, 6-2, 6-2 win. He will now take on Bernard Tomic after the Australian out-gunned John Millman 6-4, 7-6 (7-4), 6-2 in a match that finished well after midnight.

Murray, husband of Sears' daughter Kim, also did not front the media after his match.

However, 32nd-seed Sousa revealed Murray rushed to be by Sears' side in Melbourne hospital.

"I just heard that Andy went directly to the hospital. The good thing is ... (Sears') conscience, he's speaking so we hope there's nothing bad," the 26-year-old told press.

"Of course the first thing is the family and their health so I think it's very good that Andy went to (be with) him."

Word of the emergency travelled around Melbourne Park, while the pair battled away on MCA. However, Sousa said neither he or Murray had picked up on the mood shift in the crowd.

"It's kind of weird. But we are competing, we are trying to give our best to win," Sousa said.

"I mean on court you don't really realize this kind of thing - you are concentrating on your tennis."

Later in the night, the feel-good story of this year's Open, Chinese qualifier Zhang Shuai won her sixth-straight match in a row at Melbourne Park.

Zhang, who claimed the scalp of 2nd-seed Simona Halep in the first round, barely raised a sweat against American Varvara Lepchenko, winning 6-1, 6-3. She will now take on Keys for a place in the quarter-finals, a seemingly unthinkable achievement given the 27-year-old had never been past the first round of a Grand Slam until this week.

Earlier in the men's draw, Frenchman Gael Monfils weathered an early storm against compatriot Stephane Robert before winning 7-5, 6-3, 6-2.

Through the first two rounds, the 23rd-seed's serve had not been broken - but that record did not last much longer as his 225th-ranked opponent raced to a 5-2 lead in the first set.

Somehow, Monfils won the next five games to clinch the set. From there, he was not challenged again.

With the win, the enigmatic 29-year-old equaled his best ever run at the Open, entering the last 16 for the first time since 2009. Enditem