Belgium's Kim Clijsters began her Australian Open defence with a straight-sets win over Portugese qualifier Maria Joao Koehler.
Clijsters won a surprisingly close first set before racing away with the second to win 7-5, 6-1, showing no signs of the hip injury that forced her out of the Brisbane International two weeks ago.
China's French Open champion Li Na progressed after negotiating a tough first match while third seed Victoria Azarenka laid down an early marker at the year's first grand slam.
In stifling heat Li, last year's runner-up, recovered from a slow start to down Ksenia Pervak of Kazakhstan 6-3, 6-1, after Azarenka had shown her intent with a 6-1, 6-0 demolition of Britain's Heather Watson.
Azarenka, who won last week's Sydney International and is unbeaten in 2012, needed just 67 minutes to overwhelm Watson and move into a second-round clash against Australia's Casey Dellacqua.
Clijsters was forced to work hard in the early stages by the unknown Koehler, who was playing her first ever main tour match outside Portugal.
The 19-year-old from Porto only managed to land 35 per cent of her first serves in the opening set but scrapped hard for every point, playing well above her world ranking of 223.
But, when serving at 5-6, her lack of experience told and Clijsters attacked, quickly racing to love-40, then wrapping up the first set courtesy of a Koehler double-fault.
Clijsters seized control and broke twice more in the second set to cruise to a comfortable win.
"I'm feeling good and I'm happy to say that (the injury) is all behind me," the 28-year-old world number 14 said.
"I've always loved coming to Australia and that feeling is stronger after last year. Being on this court brings back a lot of memories."
Pervak, the world number 40, matched fifth-seeded Li for much of the first set as the two players traded a series of booming groundstrokes.
However, the Chinese star always looked the more threatening and once she broke Pervak to open a 4-2 lead she never looked like losing.
"It's not easy (playing in that heat)," she said.
"I'm not used to it. I came down from Sydney, but there it was only like 20 degrees. It was really tough today."
Azarenka dominated Watson in the first match on centre court as she pressed her claims for a maiden grand slam title.
The world number three was far too powerful for Watson, blasting 15 clean winners and forcing 14 errors from the Englishwoman's racquet.
Azarenka is one of six players in the draw who could finish the tournament with the number one ranking, and she acknowledged it was time she stood up and won a major tournament.
"These are always the goals for me. I'm such a competitor that I always put challenges on myself on the court, off the court, and I try to reach them," she said.
Dellacqua recorded the first victory by a local player on day one, downing Serbia's Bojana Jovanovski in straight sets.
It was Dellacqua's first win at a grand slam tournament in two years, during which time she has battled a string of injuries.
Jovanovski had beaten the 26-year-old Dellacqua at their previous meeting at the Brisbane International earlier this month.
But she struggled to get any rhythm on Monday, holding serve only twice in seven attempts.
Eighth seed Agnieszka Radwanska, who also has a chance of becoming number one, came back from a set down to beat colourful American Bethanie Mattek-Sands 6-7 (12-10), 6-4, 6-2.
The highest profile casualty on day one was 19th seed Flavia Pennetta, who fell to Russian qualifier Nina Bratchikova 6-3, 1-6, 6-2.
AFPTags: australian-open, tennis, sport, melbourne-3000, vic, australia First posted January 16, 2012 13:16:55