Germany's Lena Schoneborn remained at the head of the field in the Olympic women's modern pentathlon after the third leg of the demanding five-sport event here Friday.

The world number three was had an overall total of 3,412 points, 48 ahead of both Egypt's Aya Medany, the silver medallist at the world championships in Budapest in June, and Britain's Heather Fell, who was fourth in Hungary.

But, ominously for the leading trio, French world champion Amelie Caze had moved up into fourth after posting the second fastest swimming time behind record-breaking US veteran Sheila Taormina.

Hungary's Zsuzsanna Voros, the defending Olympic champion, was down the field in 19th place.

Taormina, whose time of 2:08.86, was a new record for the swim in women's modern pentathlon, had made history just by taking her first shot in the opening 10-metre pistol competition.

The 39-year-old is competing in a record-breaking third different sport in her fourth Olympic Games.

She won gold as a swimmer in the 4x200 metres relay at the 1996 Games in Atlanta, before featuring in the triathlon in Sydney in 2000 and again four years ago in Athens.

But after the shooting and fencing sections she was bottom of the overall standings and even her excellent swim only left her 32nd out of 36.

It was in the fencing that Schoneborn, who won 28 of her 35 bouts, and Fell, watched by Prime Minister Gordon Brown, surged up the standings.

Now the athletes go on to compete in a show-jumping competition where, unlike other Olympic equestrian events, they won't be riding their own horses.

Wet conditions, which caused heavy going, were blamed by officials for the several falls and multiple refusals which took place during the show-jumping phase in the men's pentathlon here Thursday although some riders were critical of the quality of the horses provided by hosts China.

The cumulative points score after four events in a modern pentathlon is converted into seconds of advantage ahead of the 3,000 metres where the overall leader is the first off in a staggered start.

This means that whoever is the first across the line is also the winner of the gold medal.

The modern pentathlon, a sport created by the French founder of the modern Olympics, Baron Pierre de Coubertin, is a demanding event featuring five disciplines based on the abilities that might have been expected of a military messenger in the army of Napole