the Australian Open at the first round stage -- for the first time in his career -- after losing to fellow Spaniard Fernando Verdasco 7-6 (8-6) 4-6 3-6 7-6 (4-7) 6-2 in a thrilling match between the two left-handers that lasted four hours and 40 minutes.
Mallorcan Nadal had ended 2015 in positive fashion, making finals in Beijing and Basel then reaching the semis at the year-end championships before losing to Novak Djokovic, and the world No. 5 might have gone 3-0 up in the decider had Verdasco not saved a break point.
It's a defeat -- only the third time in 17 encounters Verdasco had beaten his fellow Spaniard -- that will raise further questions as to whether the 29-year-old Nadal is still capable of challenging for the grand slams.
His last grand slam triumph came at the French Open in 2014, while 2015 saw him dumped out of Wimbledon in the second round and the third round at the U.S. Open.
"The match is a tough one to lose for me obviously," Nadal told reporters. "I have been playing and practicing great and working so much. It is tough when you work so much and arrived at a very important event and you're going out too early.
"I know I did everything that I could to be ready for it. It was not my day. There is no more things to do other than keep practicing hard and keep practicing the same way that I have been doing for the past four, five months."
Verdasco, who hit 20 aces, 10 return winners and 57 groundstroke winners, advances to play Dudi Sela of Israel in the second round.
"I just started hitting winners, I don't know how," Verdasco told reporters. "I was just closing the eyes and everything was going in.
"I will keep it up and try playing like this. Now I focus on the second round. Let's go."
There was also a shock in the women's draw on the second day of the Australian Open as second seed Simona Halep crashed out in the opening round.
The Romanian, who reached the quarterfinals of the competition in the previous two years, bowed out at the first attempt this time around after losing to China's Zhang Shuai 6-4 6-3.
Zhang, ranked 133rd in the world, advanced into the main draw as a qualifier and left the court in tears Tuesday after recording her first victory in a grand slam at her 15th attempt.
The 26-year-old Zhang was dominant from the off against Halep, who has now fallen at the first hurdle three times in six visits to Melbourne.
"I am excited about today, I played so well," Zhang told reporters. "I think in my life, [it was] the best tennis.
"First win -- I'm so happy, so excited. I want to say thank you to my parents, my coach. Thank you everybody for supporting me."
Zhang will face France's Alize Cornet in the second round.
Halep's was not the only surprising exit in the women's draw, with eighth seed Venus Williams knocked out by Johanna Konta.
Konta, ranked 47th in the world, claimed a 6-4 6-2 victory over seven-time grand slam champion Williams -- who had her left thigh heavily strapped -- to reach the second round.
"I'm very satisfied with how I dealt with the situation," British No. 1 Konta told reporters.
"It was hot out there. I was playing an incredibly great player. That's no secret."
Elsewhere, other seeds in the women's draw fared better.
Spain's Garbine Muguruza, seeded third, saw off Anett Kontaveit of Estonia with a 6-0 6-4 win, while seventh seed Angelique Kerber progressed with a 6-7 7-6 6-3 victory over Misaki Doi.
Ana Ivanovic, seeded 20th, also booked her place in the second round -- the Serb defeated Australia's Tammi Patterson 6-2 6-3 -- with Belarus' 14th seed Victoria Azarenka beating Alison Van Uytvanck of Belgium 6-0 6-0.
Murray makes it through
Andy Murray cruised into the second round after defeating Alexander Zverev of Germany 6-1 6-2 6-3.
The second seed controlled the clash throughout against an opponent he swept aside earlier in the month at the Hopman Cup.
Murray, a four-time finalist at the Australian Open, will now face Australian Sam Grot in the second round.
"It got tough at the end," Murray told reporters. "A lot of long games and rallies and Alex fought right through to the last point, so that made it very competitive at the end.
"It was obviously tough conditions today: it started to get very hot when the clouds went away. So I was glad to get it done in straight sets."
The Brit has previously said he will leave the tournament in Melbourne if his pregnant wife Kim goes into labour. She is due to give birth in February, with the Australian Open ending on January 31.
"Kim will message my team if anything is going on during the matches," Murray said.
"And then we'll see what happens!"
Fourth seed Stan Wawrinka progressed to the second round after his opponent Dmitry Tursunov was forced into early retirement through injury, while Spain's David Ferrer, seeded eighth, beat Peter Gojowczyk of Germany 6-4 6-4 6-2.
Elsewhere, there were also first-round wins for seeds John Isner, Milos Raonic, Bernard Tomic and Fabio Fognini.