Melbourne: Defendingchampions Roger Federer and Amelie Mauresmo overcame early nerves to negotiatethe first round of the Australian Open on a day overshadowed by brawlingSerbian and Croatian fans.

Wearing the national colours of the bitter Balkan rivals, the Serbian andCroatian fans clashed after taunting and hurling insults at each other.

Dozens of police were called in and ejected around 150 of them afterconfiscating their tickets.

"They were mostly Serbians ejected as they were upsetting theCroatians," Victoria Police spokeswoman Katherine Jess said.

Tennis Australia chief executive Steve Wood said there were no injuries orarrests and security staff had acted swiftly to end the brawl.

Unaware of the melee, the Fed Express, bidding for his third Australian Opentitle and 10th Grand Slam, stuttered through his first set against German BjornPhau before finding his groove to post a 7-5, 6-0, 6-4 win.

It sets up a second clash with Swede Jonas Bjorkman or Frenchman OlivierPatience.

Under cloudy skies and with a smoke haze from bushfires in the air, theSwiss world number one admitted he had to battle hard before getting the upperhand.

"I'm happy to be through because it looked like it was definitely goingto head for a first set loss," he said.

"But I came through, that's the most important thing."

Andy Roddick, who beat Federer in the Kooyong Classic final on Saturday, wasalso given a fright, losing the first set after a mammoth tiebreak to Frenchwildcard Jo-Wilfried Tsonga before going 2-5 down in the second.

The American pulled himself together and rallied to a 6-7 (18/20), 7-6 (7/2)6-3, 6-3 victory and will play another Frenchman Marc Gicquel in the secondround.

"It was a combination of being a little bit tight in the tiebreaker anda little bit uncomfortable because he was serving real well," Roddicksaid.

"I got too excited and rushed it a little bit. But it got better as Iwent along.

Other seeds through included ninth seed Mario Ancic of Croatia, the evergreen Dominik Hrbaty of Slovakia,seeded 22, and former French Open champion Juan Carlos Ferrero, seeded 24.

Mauresmo, the second seed behind Maria Sharapova, fought past Shenay Perryof the United States6-3, 6-4 in one hour 14 minutes.

The Frenchwoman, who also won Wimbledonlast year for Grand Slam success after a decade of frustration, proved toopowerful for Perry but it was a decent workout.

She next plays Olga Poutchkova of Russiawho beat Poland'sMarta Domachowska.

"(It's) not yet quite the feeling that I had at the end of thetournament last year but the first match is never easy," said the theGeneva-based 27-year-old, who has shaken off her tag as choker who froze at keymoments.

"I tried to get my rhythm but I'm glad to go through and it's great tobe back here."

Other women safely through included Russian seventh seed Elena Dementieva,Serbian 11th seed Jelena Jankovic and Czech Republic 10th seed NicoleVaidisova.

Serena Williams, coming back from a four-month injury layoff and unseeded,begins her drive for a third Australian Open crown with a first round matchagainst 27th seed Mara Santangelo of Italy in the evening session.

Third seeded Russian Svetlana Kuznetsova, the 2004 US Open champion, playslocal hope Jessica Moore later Monday while compatriot and sixth seed NadiaPetrova takes on Asian stalwart Tamarine Tanasugarn.

Kim Clijsters, who won both the Hong Kong Classic and Sydney Internationaltournaments in the lead-up to Melbourne, is on court today (Jan 16, 2007).