SONIA O'SULLIVAN'S Olympic preparations are precisely on schedule after she reduced a world class field to total submission in the 1,500 metres in Oslo last evening.

There were no excuses, no hard luck stories from the opposition after O'Sullivan had broken the four minute barrier to beat Britain's Kelly Holmes comprehensively, in three minutes 59.91 seconds.

Surprisingly, Maria Mutola was run out of third place on the charge to the line by Australia's Margaret Crowley with Sinead Delahunty returning career best figures of four minutes 4.51 secs in sixth place.

The immediate reaction from the media was to install the Irish woman as favourite for the 1,500 metres in Atlanta after what she herself, described as her most gratifying win since her world championship success.

O'Sullivan dictated the tactics and the tempo from the off. And yet, there was a moment of raw apprehension going down the back straight for the last time, when Holmes, who had tracked the winner diligently throughout, suddenly loomed at her shoulder.

Reacting instantly, O'Sullivan went into a different gear and by the time they had reached the top bend, the roles had been defined so starkly that Holmes already knew she was running for second place. Typically, she continued to battle to the end, but on this occasion there was to be no repeat of last year's upset in Gateshead, when the English girl held all the advantages in the drive for the finish.

It had been an imperious run by the Irish woman, flawed only by what appeared to be a temporary loss of concentration on the last lap and the point was acknowledged later.

Meeting Holmes as they walked off the track, she said: "Thanks for waking me up - I needed that". And one sensed that she wasn't merely observing the niceties of the track. The implicit message was that an important put down had been delivered in the context of the Olympic Games and the world champion made no attempt to disguise it.

Definitely, there was a message there for the others," she said. "I needed to make a point to everybody and the encouraging thing for me, was that I responded so quickly when Kelly got to me.

"It was good to be able to get back on stride almost immediately and once I had survived that situation, I knew that it was my race. I've been slow to get going this season but now I think I'm back where I want to be. I felt good running off that pace and that, too, is very reassuring."

The dimensions of the task awaiting O'Sullivan in the 5.000 metres in Atlanta were shown to be formidable when her arch rival, Fernanda Ribeiro produced a marvellous counter charge to snatch victory from the Romanian, Gabriela Szabo.

It looked all over for the Portuguese athlete when, after taking the lead from Szabo at 4,000 metres, she, herself, was overtaken by the Romanian as they came off the last bend.

At that point, all Szabo had to do was to keep her rhythm and her focus but, incredibly, she appeared to ease up in the last 20 metres in the belief that she had the race won. That shaft of hope was enough to get Ribeiro going and in a remarkable surge, she regained the lead on the line.

Valerie Vaughan's failure to show meant that Kathy McCandless got the third Irish nomination for the Olympic 5,000 metres but just to make sure, she returned career best figures of 15 mins 28.28 secs in eighth place.

Earlier, Nick Sweeney, one of Ireland's better prospects for the Olympic Games, tumbled out of the discus competition after an error strewn series of three fouls.

Sweeney, in trouble from the start when he was unluckily adjudged to have fouled, lost his balance with his second throw - the best of the three at 64 metres and then couldn't prevent himself stepping on the rim when he sought to retrieve credibility on his last visit to the circle.

"That first throw was the crucial one, for in my opinion and those around me, I never touched the rim," he said.