Nadal suffered one of the worst Grand Slam results of his career as he was stunned by fellow Spanish left-hander Fernando Verdasco in a five-set thriller which recalled their epic 2009 semi-final.
Halep, the women’s world number two, soon followed him out in an almighty upset by Chinese qualifier Zhang Shuai — who wept freely as she won her first Grand Slam match in 15 attempts.
While Halep’s defeat to Zhang, the world number 133, came out of the blue, it was Nadal’s loss which created concern as the 14-time Grand Slam-winner increasingly looks a fading force.
Nadal, 29, has only ever lost once before in a Grand Slam first round, at Wimbledon 2013, but he has not gone further than the quarter-finals at the majors since he won the 2014 French Open.
“It’s tough, but at the same time, I know I did everything that I can to be ready for it,” said Nadal, after 45th-ranked Verdasco’s 7-6 (8/6), 4-6, 3-6, 7-6 (7/4), 6-2 win in four hours, 41 minutes.
“Was not my day. Let’s keep going. That’s the only thing. There is no more thing to do than keep practising hard, keep practising the same way that I was doing the last four, five months.”
The big upsets at least drew attention away from a match-fixing controversy which hit the start of the tournament after a report said top players had been under suspicion but never punished.
Andy Murray, a four-time finalist who is seeking his first win in Melbourne, dispatched Germany’s Alexander Zverev 6-1, 6-2, 6-3 in hot conditions to move into the second round.
Afterwards the world number two, who is awaiting the imminent birth of his first child and has pledged to race home if his wife goes into labour, immediately checked his phone for news.
“I’m hoping my phone hasn’t been buzzing in my bag. Kim will message my team if anything goes on and we’ll see what happens,” he said.
– Age irrelevant –
Rising star Garbine Muguruza beat Estonian debutante Anett Kontaveit 6-0, 6-4 in one hour exactly — and immediately set her sights on dethroning Serena Williams in the final.
“To win the Grand Slam here you are going to have to beat Serena (Williams). It will be great if I can play against her,” said the confident Spanish world number three.
Temperatures of 33 Celsius (91.4 Fahrenheit) took their toll and Diego Schwartzman was stretchered off after retiring in the fourth set against John Millman with cramps.
While Murray and Muguruza motored through, seven-time Grand Slam champion Venus Williams suffered an early exit when she lost to British number one Johanna Konta 6-4, 6-2.
Williams, 35, was the oldest player in the women’s draw but Konta said it would be “silly” to focus on the American’s age.
“I think it would be silly to look at Venus’ age and somehow consider that as a reflection of her level,” said the 24-year-old.
“I think it’s irrelevant how old she is because she’s such a champion with so much experience and so much knowledge about the game.”
Milos Raonic, who is now working with Carlos Moya and beat Roger Federer in this month’s Brisbane final, breezed past Lucas Pouille and into the second round.
But it was a different story for Gilles Muller, who came through four tie-breaks to beat Fabio Fognini, but not before the Italian showed flashes of his famous temper.
Jeremy Chardy had an even bigger struggle, winning the fifth-set 13-11 to finally overcome Ernests Gulbis after four hours and 43 minutes.