The dark clouds were still hovering above Roger Federer [ Images ] and Serena Williams [ Images ] when they made their first appearances at the Australian Open [ Images ] on Tuesday.

The unseasonal rain that washed out most of Monday's matches gave way to brilliant sunshine but the two world number ones were caught in their own storms.

Federer survived a real scare from Russia's [ Images ] Igor Andreev before winning his opening match 4-6, 6-2, 7-6, 6-0 while Williams lashed out at officials after her 6-2, 6-1 win over Poland's Urszula Radwanska.

Sweden's French Open [ Images ] finalist Robin Soderling [ Images ] was the biggest name to fall on a day when eight seeds were buried and a little-known Irishman suddenly found himself in the spotlight.

The notion that Federer's air of invincibility is diminishing has been one of the popular topics of conversations in the build-up to the first Grand Slam of 2010.

The Swiss master has repeatedly dismissed the notion his motivation might be waning after he achieved his lifelong goals last year - including a first French Open crown and a record 15th Grand Slam title at Wimbledon [ Images ] - but his performance against Andreev would have done little to silence the doubters.

Russia's Nikolay Davydenko [ Images ], who has beaten both Federer and Rafael Nadal [ Images ] twice in the same tournament in recent months, said he believed he was now the player everybody feared.

"I have more confidence," the sixth seed said after a 6-1, 6-0, 6-3 win over Germany's [ Images ] Dieter Kindlmann.

"I know everybody is scared to play against me."

By his own standards, Federer was below his best and got a lucky break when Andreev failed to serve out the third set but he almost laughed when he was asked if he feared Davydenko.

"Scared is a bad word. I don't like that word," he said.

"Ask a boxer if he's scared of the other guy. I don't think he's going to say yes."

Williams hardly broke sweat as she opened her title defence with a comfortable win on the Rod Laver Arena, extending her perfect record of never losing in the first round of a slam, but saved her best shots for the post-match news conference.

UNFAIRLY TREATED

Still bristling after being handed a record fine for her expletive-laden outburst at a lineswoman in New York, the American was adamant that she had been unfairly treated.

"I don't know whoever got fined like that. People said worse, done worse. I think it was a bit much," she said.

She was joined in the second round by her elder sister Venus, one of many recent Australian Open finalists who won on Tuesday, including Lleyton Hewitt [ Images ], Ana Ivanovic [ Images ] and Marcos Baghdatis [ Images ].

Novak Djokovic [ Images ], the 2008 champion, also made an impressive start when he beat Daniel Gimeno-Traver 7-5, 6-3, 6-2 in a clear intention for his plans over the next fortnight.

Eighth seed Soderling, struggling with an elbow injury, joined first day loser Maria Sharapova [ Images ] in making an early exit when he lost 5-7, 2-6, 6-4, 6-4, 6-2 to Spain's Marcel Granollers [ Images ].

"I don't know what happened I just didn't play well," Soderling grumbled.

"I started terrible and finished terrible."

Fabrice Santoro [ Images ] bid farewell to the game after his final appearance. The Frenchman retired last year but was persuaded to make one final trip to Australia [ Images ] to stretch his professional career that began in 1989 into a fourth decade.

"I was very happy to come back one more time here. No regrets," he said after his 7-5, 7-5, 6-3 loss to Marin Cilic [ Images ].

Louk Sorensen's days of anonymity ended in a flash after he became the first Irishman to win a match at a Grand Slam.

He was already the first Irishman to qualify for a Grand Slam in 25 years but his 6-4, 3-6, 6-2, 6-1 win over Taiwan's Lu Yen-hsun thrust him into an unfamiliar world.

"I don't know what's going on right now," he said. "I've suddenly got so many friend requests on Facebook."