SONIA O'Sullivan will be required to produce her fastest running of the season to date, if she is to keep her unbeaten record intact in Oslo on Friday evening.

That much emerged yesterday after the make up of the field had been announced for the 1500 metres, one of the prime pre-Olympic events which will invest the Bislett Games with more importance than ever this season.

Opposing O'Sullivan will be many of the athletes she can reasonably expect to encounter in the Olympic final, among them the reigning champion, Hassiba Boulmerka of Algeria.

After a slow start, the tempo of Boulmerka's season has quickened considerably over the last couple of weeks and now, less than a month away from the big Atlanta showpiece, she will be determined to score some important psychological points.

Also in the field is Britain's Kelly Holmes, last year's silver medallist in the world championships, whose time of four minutes 04.56 seconds made her quite the fastest at the distance in the opening months of the season.

Maria Mutola of Mozambique, whose remarkable sequence of 42 wins was ended only by a disqualification in the 800 metres semi final in Gothenburg last summer, is another with impressive credentials and there will bed some respect also for the claims of Portugal's Carla Sacremento, whose seasonal best figures of 4-05.47 are faster than those of the Irishwoman.

If the challenge ahead fazes her, it wasn't apparent in O'Sullivan's response in London yesterday when she said that she was more concerned with the challenge of producing good figures on Friday, than the fear of losing for the first time this season.

It will be a big occasion, too, for Marcus O'Sullivan and Niall Bruton who are among those listed for the huge task of denying Noureddine Morceli his expected win in the Dream Mile.

Their sense of purpose will be shared by Nicky Sweeney, the national discus champion who takes time off from his Olympic build up in Sweden to oppose Anthony Washington (US), Virgilus Alekna (Latvia) and Lars Riedel (Germany) in a competition which will feature the best six throwers in the world this season.

BLE officials were staying tight-lipped yesterday on the controversy which is building around Marcus O'Sullivan's nomination for the Olympic 1500 metres championship in Atlanta.

Privately, they reject suggestions that his name was not put forward for selection at last Wednesday's sitting of the management committee, a meeting which was subsequently adjourned to July 8th. Yet, they are not prepared to comment on speculation that the former world indoor champion will be opposed in his attempt to make a record fourth consecutive appearance in Ireland's Olympic squad.

Together with Niall Bruton and Shane Healy, O'Sullivan has already achieved the A qualifying standard for Atlanta and, in normal circumstances, his selection would merely be a formality. But there is unmistakable evidence that at least some of the Board's hierarchy believe that at 34, his inclusion is the team would not be in the best long term interests of the sport. This overlooks the fact, of course, that in last Friday's Grand Prix meeting in Paris, he produced the fastest 11500 metres run of his career, when finishing third behind Moureddine Morceli.

Building on the promise of his performance at the Mardyke a week earlier, he went over the line in three minutes 34.09 seconds, an improvement of almost half a second on his previous best, set four years ago.

That emphatically gave the lie to suggestions that he was merely marking time before following another triple Olympian, Frank O'Mara, into retirement and was" made all the more remarkable by the fact that O'Sullivan believed he is still a month off peaking for the season.

Against that, however, there is school of thought which suggests that he invalidated his claims by refusing to make himself available for selection for last year's world championships, thereby failing to fulfil an IAAF requirement.

He was also in breach of a local rule that athletes automatically exclude themselves from Olympic selection by opting out of Ireland's Europa Cup fixtures. If this regulation were strictly enforced, however, Sonia O'Sullivan, would be among those excluded.

As of now, it would seem that Marcus O'Sullivan enjoys the support of the bulk of the selectors but that could well change if another Corkman, Ken Nason, succeeds in getting an A standard within the next week.