The first Grand Slam got undwerway in Melbourne on Monday and apart from Andy Murray's defeat in the Men's Singles, there were no other upsets on day one.
Frenchman Jo-Wilfried Tsonga proved too strong for the on-form British number one as he powered his way to a 7-5 6-4 0-6 7-6 (7-5) first round victory.
The Scot failed to produce anything like his best form as a series of errors - the last of which was a loose forehand which cost him the match in a fourth-set tie-break - handed Tsonga the initiative.
The number two seed secured his place in the second round but was made to work hard in his opening match against qualifier Viktor Troicki.
The Spaniard struggled to find his rhythm on Rod Laver court but eventually ground out out a 7-6 (7/3) 7-5 6-1 win over the Serbian in two hours and 34 minutes.
Troicki, ranked 126 in the world, was making his debut at the first grand slam of the year, while Nadal was among the pre-tournament favourites to challenge for the title held by Roger Federer.
World number six Andy Roddick made short work of Czech Lukas Dlouhy.
In ideal conditions with the temperature hovering in the low 20s and a gentle breeze blowing, Roddick advanced in only 98 minutes with a 6-3 6-4 7-5 victory that earns him a second-round berth against either compatriot Donald Young or German Michael Berrer.
Roddick lashed 28 winners and committed only 11 unforced errors in the polished display, a year after he was beaten by world number one Roger Federer in what was his third semi-final appearance in five years at Melbourne Park.
There was also little trouble for world number four Nikolay Davydenko in his campaign-opener against Frenchman Michael Llodra, Davydenko recovering from a break down early in the match to race away to a 7-5 7-5 6-3 victory.
Spaniard Tommy Robredo had looked to be on his way out when German Mischa Zverev opened up a two-set lead, but the 11th seed rallied brilliantly on the way to a 4-6 2-6 7-6 (7/2) 6-4 7-5 triumph.
Murray was not the only seeded casualty, with Argentinian number 18 Juan Ignacio Chela also sent packing by Spaniard Guillermo Garcia-Lopez, 6-4 6-2 1-6 6-2.
But Ivo Karlovic, Paul-Henri Mathieu, Jarkko Nieminen, Gilles Simon and Igor Andreev all advanced.
Karlovic, the Croatian 20th seed who ended Lleyton Hewitt's Wimbledon defence in the first round in 2003, ousted British qualifier Jamie Baker in four sets, 6-4 6-4 6-7 (1/7) 6-4.
French number 23 seed Mathieu enjoyed a straight-sets passage against Romanian Victor Hanescu, while 31st-seeded Russian Igor Andreev got through in four sets and Finnish number 24 seed Nieminen and French 28th seed Simon both needed five sets to get through.
In the women's tournament, World number three Jelena Jankovic had to overcome injury, a dogged opponent and even an errant driver to reach the second round of the Australian Open after an extraordinary first-round escape.
The 22-year-old, who came into the tournament with a thigh injury sustained during the Hopman Cup in Perth, needed just over three hours to beat little-known Austrian Tamira Paszek 2-6 6-2 12-10 in a match in which she came from 4-1 down in the deciding set and saved three match-points.
Jankovic's struggle was in stark contrast to the dominance of tournament favourites in defending champion Serena Williams and world number one Justine Henin, who both progressed in straight sets, while Amelie Mauresmo needed three sets to get past Tatiana Poutchek, 6-7 (6/8) 6-0 6-0.
Comeback mum Lindsay Davenport and Russian glamour girl Maria Sharapova have set up potentially one of the most exciting second-round clashes in the history of the Australian Open.
The pair, who between them have won five grand slam tournaments, will clash on Wednesday.
Other first-round winners on day one included Australians Jessica Moore and Cassely Dellacqua in a rare success for the local women as well as Romania's Edina Gallovits, China's Meng Yuan, Germany's Angelique Kerber, Russia's Olga Poutchkova, American Jill Craybas and France's Aravane Rezai.
And other seeded women to advance included Russian number 11 seed Elena Dementieva, French number 13 seed Tatiana Golovin, Israel's 17th-seeded Shahar Peer and Belarus' number 26 Victoria Azarenka.
Number 32 seed Julia Vekulenko departed after succumbing to compatriot Elena Vesnina.
