World number one Roger Federer and women's favourite Serena Williams got off to flying starts as a mysterious drugs controversy emerged at the Australian Open.
Federer, the overwhelming men's favourite and defending champion, sailed into the second round after ruthlessly demolishing France's Fabrice Santoro 6-1, 6-1, 6-2 at a sun-baked Melbourne Park.
"It was a good start. I think the start of the match was important for me, you know. That set the tone for the rest and I never really gave him a chance to get back into the match," said Federer.
Santoro, who often shook his head in appreciation as Federer passed him with a flow of winners, said the Swiss star was head and shoulders above his rivals.
"He's the best. He's much better than anyone on the tour, but maybe someone can beat him," the 32-year-old said.
Williams, the 2003 champion, was no less clinical as she walloped Frenchwoman Camille Pin 6-1, 6-1 in just under an hour to advance comfortably in the women's singles.
Federer and Williams were the two biggest names in action early Monday, as news of a doping controversy involving Russia's US Open champion Svetlana Kuznetsova threatened to overshadow the first day's play.
Kuznetsova powered into the second round in 43 minutes with a 6-1, 6-1 win over American qualifier Jessica Kirkland.
But the 19-year-old fifth seed's win was lost in a doping cloud following reports of a positive test at an exhibition event in Belgium last December.
Belgian officials said a player had failed a drugs test at the tournament, which involved former world number one Justine Henin-Hardenne, Kuznetsova, fellow Russian Elena Dementieva and Frenchwoman Nathalie Dechy.
Officials ruled out Henin-Hardenne as the culprit -- but did not disclose which of the remaining three players had failed the test.
Kuznetsova said she not received any notification from either Belgian or Russian authorities and admitted she was baffled by the reports.
"I don't know anything about it. Nobody has contacted me about it," said Kuznetsova. "All I know is that somebody wrote something in a newspaper. But that's it, nothing else. I would wonder how it could have happened."
Though men's tennis has been embroiled in doping controversies in recent years, cases on the women's tour have been rare.
Kuznetsova said she was convinced that the women's game was relatively drug-free. "I'm sure that most of the players are pretty clean," the big-hitting right-hander said.
While Kuznetsova was fielding questions about doping, Williams created one of the day's talking points with her striking outfit.
Warming up in lime-green and white knee-high boots, she stepped out of her right shoe in mid-rally during the second game.
"I have a bad habit, I always slip in and out of my shoes like they're flip-flops," Williams said.
"So I never tie them. I guess I forgot to tie them," said Williams, playing her first match since the WTA Tour Championships in Los Angeles last November. "I was a little nervous going into it, but after the first game I was okay. I thought if I just get the first game then I'll be alright," she added.
Williams, meanwhile, criticised Belgian officials for leaking news of the drugs case before test results had been confirmed.
"I think there's no need to accuse anyone of anything unless there's hard proof," Williams said.
Williams and Kuznetsova were among the first women to advance, with other top-ranked players including Russian fourth seed and Wimbledon champion Sharapova playing later Monday.
Second-seed Amelie Mauresmo of France faces Australian hope Samantha Stosur in a night match on the Rod Laver Arena centre-court.
In men's matches, Dominik Hrbaty became the first seed to advance when his Swedish opponent Robin Soderling retired hurt with the Slovak leading 6-4, 6-2, 1-0 in their first round match.