Tennis: O'Brien follows Baltacha's victory march in Melbourne

The Hull-born 23-year-old won 6-3, 6-3 to progress past the first round of a grand slam for just the second time in her career.

O'Brien's best ever result at a major was reaching the second round at Wimbledon in 2007 and today's confident display, against a player ranked three places behind her in 90th, ensured she would at least match that.

O'Brien was first on Court Four today and, with sunny conditions greeting the players, she quickly found her stride, breaking her Austrian opponent in the fifth game to go 3-2 ahead and then with Mayr serving to stay in the set broke again to take the advantage. Mayr broke early in the second set, but from there on in her serve let her down.

O'Brien pounced on the opportunity and broke on three consecutive occasions to surge ahead before wrapping up the match when Mayr dumped a forehand into the net.

O'Brien admitted she had put pressure on herself to perform against a player ranked below her. "I knew it was a good opportunity. I had a good draw and I knew I had to go out and compete," she said. "I think I dictated the play today and made her do the running and wore her down. I think it was a good solid performance.

"I'm trying to add aggression to my game. There were a few points I was disappointed with where I let her in, but the first match of a grand slam is always tough. I think I settled down well though."

O'Brien will play eighth seed Jelena Jankovic after she won her first-round match against Monica Niculescu 6-3, 6-0.

Defending champion and world No.1 Serena Williams had few problems with teenager Urszula Radwanska, booking her place in the second round 6-2, 6-1.

Williams came into the tournament with suspicions she was struggling with a knee injury and while she appeared with a large strapping on her right thigh, the American did not look hampered in her movement.

The 28-year-old had too much firepower for Radwanska as she fired 26 winners compared to just 13 from her 19-year-old Polish opponent.

In the men's singles, world No.1 Roger Federer survived an uncharacteristically sloppy display to edge past a battling Igor Andreev. The Swiss maestro recovered from losing the opening set and, while not completely convincing, wrapped up the match 4-6, 6-2, 7-6 (7/2) 6-0 in two hours and 44 minutes.

It was the first time in Federer's past 25 first-round grand slam matches that he had been taken past three sets. That was testament to some big shot-making from Andreev, the world No.37, whose aggressive style forced the top seed into some unlikely unforced errors.

After a closely-fought battle the turning point came at the end of the third set when Andreev failed to take three set points on his serve, before losing the tie-break.

The Russian, who had taken Federer to five sets in their previous meeting at the 2008 US Open, then meekly conceded the fourth set and the match in quick time.

"It was a tough third set, I definitely got lucky to get out of that one," Federer said afterwards.

"I prefer easier matches, but this worked."

Federer uncharacteristically conceded the first set after having claimed the opening break.

The Swiss immediately handed the advantage back following some loose shot making, before Andreev gave himself a chance to serve for the set when he fired back-to-back winners.

The 26-year-old made no mistake to take the opener in 41 minutes on the back of 10 winners.

Federer had looked lethargic in the face of Andreev's free swinging, but raced into a 3-0 lead at the start of the second and he did not let his advantage slip this time.

Andreev, however, continued his full throttle shot-making and again unsettled Federer in a pulsating third set. After trading early breaks of serve the pair both failed to serve for the set.

Andreev had his chance at 6-5, but passed up three set points as it went to a tie-break, where the Russian was made to pay.