Michael Johnson's challenge for more Olympic gold is up and running smoothly after a captivating start to the track and field programme at Sydney early this morning.

For all the doubts born of an injury sustained during the American trials, Johnson's first defence of the 400 metres title was never going to prove much more than an opportunity of making himself familiar with the massive Olympic stadium.

And thus it proved as the champion, in that familiar recognisable head back, upright style, eased through to the second round in a time of 45.25 seconds in the seventh of nine heats.

Only the Briton, Sean Baldock, running on the inside lane, had the temerity to try and match strides with Johnson. It proved little more than an empty gesture, however, as the American simply flowed away from his rivals over the last 120 metres.

The growing pressures of the next few days will doubtless extract a suitable response from Johnson but alas for Ireland's 400 metres representative, Tomas Coman, the battle is already over.

After flattering briefly in the middle stages of the race, Coman was already running low on strength turning into the home straight and eventually finished fifth in 46.17 seconds in a race won by another American, Antoni Pettigrew in 45.62 seconds.

Coman was every disappointed afterwards. "I had to work hard to make up ground in the middle stages of the race and it cost me over the last 100 metres.

"I tied up completely down the finishing stretch and that's not typical of me. I thought I would do better but unfortunately that was my shot on the day."

Also out is the Belfast sprinter, Paul Brizzell, who saw his hopes of progressing in the 100 metres evaporate after an untidy start. By the time he got going, it was already a lost case for Brizzell, who finished sixth in 10.62 seconds, behind the impressive Obadele Thompson of Burundi.

As expected, Maurice Greene and Ato Boldon went through to the next round of the 100 metres without undue problems but remarkably, the experienced Canadian Bruny Surin could finish only fourth in the heat dominated by America's Curtis Johnson.

The honour of winning the first track race of the Games went, not inappropriately, to the redoubtable Maria Mutola of Mazambique. Running in the opening heat of the women's 800 metres spoiled a cherished Australian dream by relegating the local runner, Tamsyn Lewis to second place in a time of one min 59.88 seconds.

As predicted, there was a near capacity crowd of 80,000 in the stadium for the start and Lewis looked like giving them the result they coveted when she swept into the lead on the last lap.

But Muotola was not in the mood to heighten the sense of occasion and with the inevitability of night following day, she caught the Australian some 30 metres out to put her title challenge away to the perfect start.

Mozambique track queen Mutola took her first step towards securing her country's first Olympic gold when she cruised to victory. The 28-year-old 1998 Commonwealth Games champion was never pushed as she came home in 1:59.88, well outside her personal best of 1:55.19.

"Everything is going well, but you never know. This is the Olympic Games, anything can happen," she said.

Her title dreams were boosted when arch-rival Ludmila Formanova failed to finish. The 800-metres world indoor and outdoor champion pulled off the track 200 metres from the end with an ankle injury.

She left the track in tears, but later spoke, confirming her ankle had been hurting for several months. "I think an operation will be necessary," said Formanovo, who had not competed in two months.

There was joy too for Kelly Holmes as the British girl confirmed her recovery from the spate of injuries which at one time threatened to end her career, with a fine win in Heat four in a time of two minutes 01.76 seconds.

Holmes has never been short of courage in head-to-head situations and after the American Hazel Clark and Russia's Nataya Tsyganova had loomed at her shoulder at the entrance to the finishing straight she found an extra gear to move clear.

The Clark dynasty were not to be denied, however, and Hazel's sister, Jearl Miles Clark, duly salvaged family respectability by winning her heat in two minutes 01.79 seconds.

Those seeking to qualify by the back door as fastest losers always have the advantage when running in the last of the preliminaries. And this was no exception as the Austrian, Stephanie Graf towed the field through in the fastest figures of the day - 58.39.

Sadly, it still wasn't enough however, to earn the controversial British runner, Diane Modahl a place in the semi-finals.

Meanwhile, there was more bad news for the Irish when Terry McHugh, the most experienced of the Irish team, failed to survive the preliminaries in the javelin competition.

McHugh, in his fourth appearance, in the summer Games, was a below below his seasonal best with an best effort of 79.90 metres.