O’Sullivan was troubled by a hamstring strain but returned to full training at the weekend.
“It was only a minor thing and she is OK again. She was back in full training at the weekend,” Irish Track and Field Manager Michael Quinlan said yesterday.
“But with the Olympic Games already underway and the athletics competitions a matter of days away there was always going to be some concern. But it appears to have been something very small.
“Her coach, Michael Lane, was here in the Athletes’ Village for a couple of days doing some technique work with Olive Loughnane and he was able to assure us everything is now all right.
“She had two hard training sessions over the weekend and is scheduled to have another session today.”
After some good early season performances at the Grand Prix in Tijuana and the World Cup in Naumburg, the Kerry woman suffered a back injury which affected her technique.
She pulled out of the Grand Prix in La Coruna after two red cards and was then disqualified at the National Championships in Morton Stadium.
But those worries seem to have passed as she aims to build on her silver medal success at last year’s world championships in Paris.
The field includes world champion Olimpiada Ivanova and another Russian, Yelena Nikolaya, who won the world cup in Naumburg.
Ivanova posted the second fastest time in the world at 1:26:54 in Cheboksary in June. There is a strong Asian contingent, with China’s Hongjuan Song, who leads the current list with a best of 1:26:46, and young Chinese walker Jing Jiang, who took silver in Naumburg. The Olympic champion from Sydney, Liping Wang, is also set to compete.
Robert Heffernan, who will get the Irish challenge underway in the men’s 20k walk on Friday morning, is also fully fit.
“He is in flying form and we can expect a big performance from him,” Quinlan said.
“He is as fit as possible and has had a long stretch without injury. He was unfortunate last season but he has put all that behind him.
“He enjoys the big occasion and always performs well at championship level. He has the right temperament for it.”
Athletes are sparse at the Irish camp at the moment but that is all set to change.
High jumper Adrian O’Dwyer arrived last night and James Nolan, who also competes on Friday in the 1,500m, touches down today and O’Sullivan and Heffernan will fly in tomorrow.
“The atmosphere is very good in the camp right now,” Quinlan said.
“Obviously the performances from Andy Lee and the rowers at the weekend had the place buzzing so we are all hoping that this can be maintained.
“So far practically everybody has performed well.”
Michael Williamson from Belfast will be in action at the Olympic Aquatic Centre today when he goes in the sixth heat of the Men’s 200m Breaststroke.