Federer is trying to win his 10th Grand Slam title

Roddick came through a serious test of nerve against French wildcard Jo-Wilfried Tsonga in Melbourne.

The sixth seed, who beat Federer in an exhibition last week, eventually won 6-7 (18-20) 7-6 (7-2) 6-3 6-3.

Meanwhile, Federer was unusually inconsistent in seeing off Germany's Bjorn Phau 7-5 6-0 6-4.

News conference: Roger Federer

Interview: 26th seed Marat Safin

The Swiss came back from a break down in the opening set before reeling off 11 straight games, but then let a lead slip in the third before finally finishing off Phau.

I think I got a little first-round jitters Andy Roddick

"I got broken in the first set three times, and that makes you a little bit nervous," said Federer. "You try to stay cool, but I got a little bit nervous."

Federer now meets Sweden's Jonas Bjorkman, who fought back from a two-set deficit to beat Frenchman Olivier Patience 5-7 4-6 6-0 6-1 6-2.

Last year's runner-up, Marcos Baghdatis, won a punishing encounter against Rainer Schuettler, who was struggling with flu and had to call a medical time out in the third set.

The Cypriot, backed by a large contingent of his countrymen, came through 6-4 2-6 6-3 6-2.

"I didn't feel good today and it was not a good match but I am just happy to get through," said Baghdatis.

"I am playing really well in practice but today I wasn't really there on the court. I tried to stay cool and calm and obviously Rainer was injured."

In typical style, Marat Safin ensured the final match of day one stretched to almost three-and-a-half hours as he battled back to defeat Benjamin Becker.

The German rattled Safin with some impressive groundstrokes and big serves, and when he took a two sets to one lead, the Russian looked buried.

But a fired-up Safin levelled to set up an intense fifth set and clinched the decisive break at 3-2 before serving out the match.

Seventh seed Tommy Robredo enjoyed a more comfortable passage to the second round, beating fellow Spaniard Ruben Ramirez Hidalgo 6-4 6-4 6-0.

Serbian 14th seed Novak Djokovic stated his intentions with a quick fire 6-1 6-1 6-0 victory against Chile's Olympic champion Nicolas Massu.

Djokovic meets Spain's Feliciano Lopez, who beat American Brian Wilson 7-6 (10-8) 4-6 6-3 7-6 (7-3).

Richard Gasquet, seeded 18, had a straightforward 6-4 6-4 6-2 win over Filippo Volandri, and ninth seed Mario Ancic eased past Go Soeda 6-4 6-3 6-2.

Roddick was in trouble against Frenchman Tsonga after losing an epic first set tie-break 20-18 and slipping a break down in the second, but the American fought his way back.

606 DEBATE: Your thoughts on the action in Melbourne

Asked if he had been worried at any stage, Roddick said: "Absolutely, to say the least. I was wondering if we were ever going to finish the tie-breaker.

"I think I got a little first-round jitters. I played better as the match went on. I hope I can get better in the second round."

He will next play France's Marc Gicquel, a 3-6 6-7 (1-7) 6-4 6-1 6-0 winner over Australian Alun Jones.

Former US Open semi-finalist Joachim Johansson retired with blisters after just two games of his match against Guillermo Garcia-Lopez.

And Czech Jan Hajek lasted only one game more against Juan Carlos Ferrero as he doubled over on court suffering the effects of a stomach bug before withdrawing.

Thailand's Paradorn Srichaphan managed to complete his match but after losing 6-4 6-2 6-2 to Israeli qualifier Dudi Sela he announced he is taking time out to deal with a wrist injury.

"It's tendonitis. You can't just play with the heart, you've got to play with your body," said Srichaphan, who could be out for two months.