Rafael Nadal lost in the first round of a major for only the second time in his career, beaten in five sets by Fernando Verdasco at the Australian Open in a reversal of their epic, 5-hour, 14-minute semifinal here seven years ago.

Fernando Verdasco rallied from a 2-1 deficit and recovered a break in the fifth set to claim a 7-6 (6), 4-6, 3-6, 7-6 (4), 6-2 win in 4 hours and 41 minutes on Tuesday, only his third victory in 17 matches against his fellow Spanish lefthander.

Nadal won his only Australian title in 2009 after beating Verdasco in the semifinals. The 14-time major winner's only other first-round exit in a Grand Slam was at Wimbledon in 2013 when he lost in straight sets to No. 135-ranked Steve Darcis of Belgium.

"It's a hard and painful loss," the fifth-seeded Nadal said. "He was playing amazing in the last set ... more aggressive than me. He took more risks than me, and he won. Probably he deserved."

There were two big upsets in the women's draw, with No. 2 Simona Halep and seven-time Grand Slam winner Venus Williams losing in the first round.

Halep, the 2014 French Open finalist, lost 6-4, 6-3 to Zhang Shuai for her third first-round loss at Melbourne Park in the past five years, but giving the No. 133-ranked Chinese qualifier her first win at a Grand Slam after 14 losses.

"It's OK. I don't want to make this match like dramatic," said Halep, who refused to blame an Achilles tendon problem that forced her out of a warmup event for her earlier loss.

Verdasco went for everything on his ground strokes, ripping 90 winners against only 37 for Nadal as he worked to the extremes to unsettle his former No. 1-ranked rival.

"To win against Rafa here coming from two sets down is unbelievable," the 32-year-old, No. 45-ranked Verdasco said. "I think I played unbelievable — the fifth set from the break that he made me, I just started hitting winners. I don't know how, just, you know I was closing the eyes and everything was coming in and I keep doing it and I was doing well."

Stan Wawrinka, who beat Nadal in the 2014 Australian final, and four-time runner-up Andy Murray advanced, along with Lleyton Hewitt, the two-time major winner who is playing his 20th and last Australian Open tournament before retiring.

French Open champion Wawrinka was leading 7-6 (2), 6-3 when his opponent Dmitry Tursonov retired with what appeared to be an upper leg injury.

After beating Halep, Zhang burst into tears when asked about breaking the drought.

"I think in my life, it's the best tennis," she said. "To win against a top-two player, I'm so happy, so excited."

Williams lost 6-4, 6-2 to Johanna Konta, her eighth first-round loss at a major.

No. 3 Garbine Muguruza and No. 7 Angelique Kerber advanced along with two-time Australian Open champion Victoria Azerenka, who closed play on center court with a 6-0, 6-0 rout of Alison Van Uytvanck.

The upset results took some focus off the match-fixing allegations that have overshadowed the first two days of the season's first major.

No. 2-ranked Murray opened with a 6-1, 6-2, 6-3 win over Alexander Zverev, checked to see there were no urgent calls from home — his wife is expecting their first child next month — and had to answer questions immediately about the reports.

"I just think that it should be tennis that does a better job of explaining," Murray said. "You have to be proactive with things like this and go and speak to the players rather than them reading about it in the newspapers or listening to it on the TV or the radio."

The BBC and Buzzfeed News published reports Monday alleging match-fixing had gone unchecked in tennis. The reports alleged 16 players, all ranked in the top 50 at some stage and half of them playing at the Australian Open, had repeatedly raised suspicion because of their results but had not been sanctioned. No players were identified.

The governing bodies for tennis rejected the claims, but Murray thought the authorities could be doing more to combat the potential for corruption.

Among the other men advancing were No. 8 David Ferrer, No. 10 John Isner, No. 13 Milos Raonic, No. 18 Feliciano Lopez and 34-year-old two-time major winner Lleyton Hewitt, playing his 20th and last Australian Open.