Sonia O'Sullivan is primed for a big performance in the final of the Olympic 5,000 metres championship on Monday (10.55 a.m. Irish time) following a convincing win in yesterday's heats in Sydney.

A nervous, mildly agitated figure when she came on track, O'Sullivan left the Olympic Stadium with the applause of the crowd paying tribute to her best run of the season. The time of 15 minutes 7.91 seconds, slow by grand prix standards, was still the best of the three preliminary races, but later she was quick to acknowledge the size of the challenge awaiting her in the final.

"We're still only at half-way in this championship and the certainty is that the second part is going to be a lot more difficult," she said. "At this stage, it's hard to know who had most left in the tank. It was still a very enjoyable experience. I was very happy with the way I ran. Now that it's over, I can focus fully on the final." It is worth recalling that the Irish champion also won her preliminary race in Atlanta four years ago before succumbing to the pressures of favouritism in the final.

Yet, it was difficult not to be impressed by either her authority during the race or her composure after it. There was no sign of the dripping perspiration which forewarned of problems ahead after her initial run in Atlanta. Now her face was unstrained, her eyes were clear and before she made her way to the area for press interviews, she had fully recovered.

However, O'Sullivan admitted to being very nervous in the build-up to the race. "It was one of those situations where you feel like walking up the stairs 10 times, packing your running shoes 10 times and then checking 10 times to make sure they were really in the bag.

"But it wasn't like that when I got to the stadium. I felt really good all through and I enjoyed the last 200 metres in particular. I opened a gap quite easily and was able to switch off and relax in the run to the finish.

"Another good sign was that I didn't feel the race go by. There are times when you think like you're a long time out there. But today I was able to break it up in my mind, watch everything that was happening around me and make certain that I was in a position to cover any breaks.

"But again, there's a vast difference in running a heat and a final. In the final, you want to be on people's shoulders, just to let them know you're around. In a race like the one today, it's all about getting into the top four and that makes things a little different.

"It wasn't my intention to sprint the last 200 metres to win the race, it just happened like that. But to get to the finish line first, without taking anything out of yourself, is always a good feeling." With O'Sullivan doing the donkey work over the first two laps, the first kilometre, run at 3.8.55 was undeniably slow. Subsequently it quickened to 6.15.02 at two kilometres and 9.18.72 at the three-kilometre mark. Here, for the first time, the two Africans, Gete Wami and Lydia Cheromei, began to do some of the front running.

The young British woman, Jo Pavey, took the initiative over the last 800 at a stage when O'Sullivan, lying in wait, was running easily in fourth place.

One got the impression that the Irish woman could hit the front any time she chose and so it proved when, in a matter of no more than 25 metres, she reined in the leaders effortlessly before sprinting down the finishing straight. In all, she required just 63 seconds to cover the last 400, leaving Pavey in second place as Wami, one of three Ethiopians in the final, claimed third position in second gear.

Gabriela Szabo of Romania was some two seconds slower than O'Sullivan over the last 400 metres while winning the third heat in 15.08.36, but yet again it is safe to assume that she was holding something in reserve for the final. Roberta Brunet of Italy, the Atlanta bronze medallist, failed to qualify from the second heat won by the Kenyan Rose Cheruiyot. But in some respects the more convincing run was that of Russia's Olga Yegorova, who could easily have swapped third place for first had she desired.

Ireland's other represetatives in the 5,000 metres both ran well below their best. Rosemary Ryan, in the same heat as O'Sullivan, suffered palpably over the last 1,500 metres to finish back in eighth place in 15.33.05. Breda Dennehy-Willis was even more disappointing in the third race. Still clearly affected by a virus, she dropped off the pace before half way to fade to 13th in 15.49.58.

But for O'Sullivan, reborn on a day when she so urgently wanted to do well, all is set fair for the big event on Monday.