Sharapova was the big loser, suffering a shock first-round loss to Maria Kirilenko, but Clijsters and Henin won easily on a day when everything, except Melbourne's fickle weather, followed the usual script.
Instead of the extreme heat that has left competitors soaked in sweat and gasping for air, the opening day of this year's first Grand Slam was severely disrupted by unseasonal wind and showers. Tournament organisers closed the giant retractable roofs on the two main courts to ensure the featured singles matches went ahead but almost 40 matches on the outside courts were left unfinished or rescheduled for Tuesday.
Juan Martin Del Potro and Andy Murray escaped the downpours to ease through while Dinara Safina, Svetlana Kuznetsova and Elena Dementieva led the Russian charge in the women's draw.
Sharapova, seeded 14th and making her first appearance at Melbourne Park since winning the championship two years ago, lost 7-6, 3-6, 6-4 to her good friend and fellow Russian Kirilenko. Unable to defend her title last year because of a shoulder injury, Sharapova was a shadow of the player who stormed to the 2008 title without dropping a set, contributing to her own downfall with 66 unforced errors and 11 double-faults. "I could be disappointed or I could just take it as it is and just go back on the court and just keep working. I choose option two," Sharapova said.
Second seed Nadal quelled speculation about his fitness with a ruthless 7-6, 6-1, 6-4 victory over Peter Luczak at a packed Rod Laver Arena.
Clijsters was runner-up to Henin at the 2004 Australian Open but had given up on the idea of winning the title when she quit the sport in 2007.
She made a fairytale comeback last year by winning the US Open, however, and launched her Australian campaign with a 6-0, 6-4 win over Canadian qualifier Valerie Tetreault. "I never expected when I said goodbye that I would be back here," Clijsters said. "Life can change and I changed my mind, and so far I haven't regretted it for a second."
Henin romped past fellow Belgian Kirsten Flipkens 6-4, 6-3 and will play Dementieva after the Russian defeated compatriot Vera Dushevina 6-2, 6-1.
Murray began his latest attempt to end Britain's long Grand Slam drought with an impressive 6-1, 6-1, 6-2 victory over South African qualifier Kevin Anderson, while Roddick dusted himself off after colliding with a line judge to defeat Dutchman Thiemo de Bakker 6-1, 6-4, 6-4.
Safina, runner-up in Melbourne last year, defeated Slovakia's Magdalena Rybarikova 6-4, 6-4 despite still trying to rebuild her fitness after suffering back pain late last year.
First-round results: (prefix denotes seeding): Men’s singles: 2-Rafael Nadal (Spa) bt Peter Luczak (Aus) 7-6 (7-0), 6-1, 6-4; Andrey Golubev (Kaz) bt Mardy Fish (US) 6-2, 1-6, 6-3, 6-3; Bernard Tomic (Aus) bt Guillaume Rufin (Fra) 6-3, 6-4, 6-4; Ivo Karlovic (Cro) bt 13-Radek Stepanek (Cze) 2-6, 7-6 (7-5), 6-4, 3-6, 6-4; 4-Juan Martin Del Potro (Arg) bt Michael Russell (US) 6-4, 6-4, 3-6, 6-2; Wayne Odesnik (US) bt Blaz Kavcic (Slo) 4-6, 6-1, 6-4, 6-2; 5-Andy Murray (Bri) bt Kevin Anderson (SA) 6-1, 6-1, 6-2; 7-Andy Roddick (US) bt Thiemo de Bakker (Ned) 6-1, 6-4, 6-4; 11-Fernando Gonzalez (Chi) bt Olivier Rochus (Bel) 6-3, 6-4, 3-6, 6-1; 24-Ivan Ljubicic (Cro) bt Jason Kubler (Aus) 6-1, 6-2, 6-2. Women’s singles: 27-Alisa Kleybanova (Rus) bt Jelena Dokic (Aus) 6-1, 7-5; 5-Elena Dementieva (Rus) bt Vera Dushevina (Rus) 6-2, 6-1; Justine Henin (Bel) bt Kirsten Flipkens (Bel) 6-4, 6-3; 3-Svetlana Kuznetsova (Rus) bt Anastasia Rodionova (Aus) 6-1, 6-2; 12-Flavia Pennetta (Ita) bt Anna Chakvetadze (Rus) 6-3, 3-6, 6-2; Yanina Wickmayer (Bel) bt Alexandra Dulgheru (Rom) 1-6, 7-5, 10-8; 15-Kim Clijsters (Bel) bt Valerie Tetreault (Can) 6-0, 6-4; Maria Kirilenko (Rus) bt 14-Maria Sharapova (Rus) 7-6 (7-4), 3-6, 6-4; 2-Dinara Safina (Rus) bt Magdalena Rybarikova (Slv) 6-4, 6-4; Zheng Jie (Chn) bt Peng Shuai (Chn) 0-6, 6-1, 6-2; 30-Kateryna Bondarenko (Ukr) bt Raluca Olaru (Rom) 6-2, 7-6 (8-6).