O'Sullivan won silver medals in the 5000 m and 10,000 m at the 2002 European Championships, and competed at her fourth Olympic Games in 2004.

[3] She is one of two women (the other Tirunesh Dibaba) who won the short and long course World Cross Country title at the same championship (1998 in Marrakesh).

[5][6] In 1992, O'Sullivan improved her personal bests in a number of distances between 800 m and 5000 m, setting six Irish national records in the process, including five in the space of 11 days in mid-August following the Barcelona Olympic Games.

Narrowly missing out on an Olympic medal was made all the more frustrating when the silver medalist from the race Tatyana Dorovskikh tested positive for a banned substance the following year.

She finished 1992 by winning the Grand Prix Final for the 5000 m. In 1993, O'Sullivan established herself as one of the world's top middle-distance runners.

Five days after the championships, at the ISTAF meet in Berlin, O'Sullivan recorded the season's best time over 5000 m of 14:45.92, which moved her to third on the all-time world list.

The next week, in London, she broke the European record for the 3000 m, beating Britain's Yvonne Murray, and setting the year's fastest time of 8:21.64.

This moved her to fifth on the all-time world list, behind the four Chinese runners who had set their personal bests at the 1993 National Championships in Beijing.

All four of these times were also new Irish records, and after this two-week period of record-breaking, O'Sullivan became a clear favourite to win any event she chose to compete in at the European Athletics Championships in Helsinki in August.

Her other 3000 m victories included the Bislett Games in Oslo on 21 July, and the Grand Prix final in Monaco on 9 September.

In the 1500 m, only two women broke 4 minutes during the year, one of whom was O'Sullivan, who clocked her best time of 3:59.91 when winning at the Bislett Games in Oslo on 5 July.

In terms of preparation for the Olympic Games held later that year in Atlanta, O'Sullivan's best event appeared to be the 5000  m, the distance at which she was the reigning world champion.

However, in the final on 28 July, she was badly affected by a stomach upset, and after starting well gradually faded away and failed to finish.

At the World Cross Country Championships, she finished 9th but helped Ireland win the bronze medal in the Team Event.

At the World Championships held in Athens, O'Sullivan produced her best 1500 m time of the year of 4:05.31 when she finished fourth in her semi-final on 3 August.

O'Sullivan had even greater disappointment in the 5000 m where she was the defending world champion, finishing only 7th in her heat and failing to qualify for the final.

On successive days, O'Sullivan won both events, and her 4 km time of 12:20 was 14 seconds ahead of her nearest rival.

At the World Cup held the following month in Johannesburg, O'Sullivan won her second major international 5000 m competition of the year, again sprinting clear of the opposition following a very slow pace.

O'Sullivan returned to training 10 days after her daughter's birth, and on 10 October, finished a half marathon in 70:05.

Back in Europe, she won the Dublin Women's Mini Marathon in June, before producing a number of quality performances on the track in her preparation for the Olympics.

The Weltklasse meet in Zürich on 11 August produced the finest 3000 m race of the year, with the first six placings registering the six fastest times of 2000.

In the final three days later, after an enthralling sprint finish, O'Sullivan won the silver medal behind Szabo in a National Record 14:41.02.

In the 10,000 m final, held on 30 September, O'Sullivan set another personal best and national record when finishing sixth in 30:53.37 performance.

O'Sullivan admitted she had been outclassed in the race by Paula Radcliffe, saying that only world record holder Wang Junxia could have beaten the British girl on the night.

She ended an excellent season by winning her second BUPA Great North Run title in a national record time of 67:19.

She started well with a win at the newly inaugurated Great Ireland Run, but she struggled during the summer Grand Prix races.

In December she finished an impressive fourth at the European Cross-Country Championships and led Ireland to silver in the team event.

[7] In 2009, she ran the Cork City Marathon, In 2012, O'Sullivan carried the Olympic flame when it arrived in Dublin on 6 June.