Photos from the matches on Day 2 at the Australian Open
Fernando Verdasco sent shock waves through the Australian Open on Tuesday by defeating Rafael Nadal 7-6(6), 4-6, 3-6, 7-6(4), 6-2 to send the former world number one crashing out in the tournament's opening round.
The first-round exit was 2009 champion Nadal's first at Melbourne Park and only his second at a Grand Slam.
Down 0-2 in the final set, Verdasco dragged himself off the canvas with a barrage of booming forehand winners, breaking Nadal twice to storm to a 5-2 lead.
He broke his compatriot a third time, sealing the match with a cross-court winner that left the Rod Laver Arena crowd stunned late in the day session.
"I just hit everything. I think I played unbelievable in the fifth set from the break," Verdasco said in a courtside interview.
"I just started hitting winners. I don't know how. I was closing the eyes and everything when I was coming in.
"I kept doing it so it went well."
After shaking hands with his opponent and the chair umpire Nadal strode quickly off the court, barely pausing to acknowledge the crowd with a wave.
Second seed Simona Halep was knocked out in the first round by Chinese qualifier Zhang Shuai, going down 6-4, 6-3 to the inspired world number 133.
The 24-year-old Romanian, who came to Melbourne nursing an Achilles injury and suffering from a cold, left Margaret Court Arena in tears after the stunning upset.
Zhang was also reduced to tears after securing her first victory in a Grand Slam main singles draw at her 15th attempt, shrieking as she secured victory after 78 minutes.
Halep was on the back foot from the start as Zhang raced into a 3-0 lead in the opening set on Margaret Court Arena.
The Romanian, who won the only previous meeting between the pair 6-1, 6-1 in 2012, rallied to get back to 5-4 but Zhang broke her serve to go one set up.
Halep took a 3-1 lead in the second set before Zhang stormed back and sealed victory when Halep failed to get her forehand return back.
"I'm so excited and happy," Zhang said in a courtside interview.
"I want to thank my coach and parents and to everybody for supporting me. I think today is my best moment."
Zhang, who will turn 27 on Thursday, will face France's Alize Cornet in the second round at Melbourne Park.
French Open champion Stan Wawrinka shook off a stubborn early challenge from Dmitry Tursunov to advance to the second round when his Russian opponent retired injured.
Wawrinka was leading 7-6(2), 6-3 when Tursunov, who had called the trainer midway through the second set to treat an apparent hip problem, indicated to the umpire he was unable to continue any further.
Tursunov, playing his first grand slam main draw match since the 2014 U.S. Open after battling a succession of foot injuries, had an opportunity to snatch the first set before the Swiss forced a tiebreak, that he won easily 7-2.
The 2014 Melbourne Park champion then pulled away to a 3-0 lead in the second set before Tursunov sought treatment on his painful hip and when the fourth-seeded Wawrinka sealed the second set, the Russian retired.
Victoria Azarenka sent a strong message to the rest of the Australian Open field with a 6-0, 6-0 hammering of Belgium's Alison Van Uytvanck in just 53 minutes in the final match of the second day's play on Tuesday.
The Belarusian produced a powerful masterclass to post the first so-called 'double bagel' of the tournament so far and only the 19th in the history of the Australian Open.
The two-times champion has been battling foot injuries and a plummeting ranking for the past two years but entered the year's opening grand slam showing a compelling return to form with victory in Brisbane, her first tournament win since August 2013.
She picked up where she left off from Brisbane as Van Uytvanck, the world number 43, earned just four points in the first four games and 10 in total during the first set.
It did not get any better for Van Uytvanck, as Azarenka swatted her aside to set up a second-round match against Danka Kovinic of Montenegro.
Second seed Andy Murray advanced into the second round of the Australian Open after a comfortable 6-1, 6-2, 6-3 victory over Germany's Alexander Zverev.
The world number two took the first two sets in 71 minutes but found the tall 18-year-old more of a handful in the third when he saved two match points before the Briton completed the victory in a little more than two hours.
Zverev, playing in the main draw at Melbourne Park for the first time, suffered a nosebleed while serving at 30-15 in the second game of the match on a sun-baked Margaret Court Arena, and was forced to call the trainer to staunch the flow.
Murray, who stayed on court and practiced his serve until Zverev returned, romped through the first two sets before the teenager produced some fight in a baseline battle in the third and made the Scot work for the win.
Canada's Milos Raonic beat Frenchman Lucas Pouille 6-1, 6-4, 6-4 to advance to the second round.
Raonic, who beat Roger Federer to claim the Brisbane International title before the season's opening Grand Slam, and is now working with Carlos Moya, will play Spain's Tommy Robredo, who beat Tunisia's Malek Jaziri 7-5, 3-6, 4-6, 7-6(7), 8-6.
It was a different story for Gilles Muller, who came through four tie-breaks to beat Fabio Fognini 7-6(6), 7-6(7), 6-7(5), 7-6(1), but not before the Italian showed flashes of his famous temper.
France's Jeremy Chardy had an even bigger struggle, winning the fifth-set 13-11 to finally overcome Latvia's Ernests Gulbis 7-5, 2-6, 6-7(5), 6-3, 13-11 after four hours and 43 minutes.
Third seed Garbine Muguruza wasted little time and raced into the second round as she beat Estonian debutante Anett Kontaveit 6-0, 6-4 in one hour exactly.
"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.
Venus Williams's dreams of winning a first Australian Open title at the age of 35 were shattered when she was beaten 6-4, 6-2 in the first round by British number one Johanna Konta.
The seven-times Grand Slam champion was named 'WTA Comeback Player of the Year in 2015' when she won three titles to move back into the top 10 in the rankings but her hopes of going one better than her final appearance in 2003 were soon dashed.
The eighth seeded American struggled to get a foothold in the match against her Australia-born opponent in the heat of Rod Laver Arena, however, and crashed out in 79 minutes.
Williams showed glimpses of her best tennis to rally from 5-0 to 5-2 in the second set but it only delayed the inevitable and 24-year-old Konta secured the upset when the former world number one netted a return.