Five-time US Olympic gold medallist Jenny Thompson says she is not under siege from the world record-breaking exploits of the Dutch ace Inge de Bruin.

Thompson is gearing up for her third Olympics here and is yet to claim an individual gold medal at the Games having shared in the success of relay events.

Just when she appeared poised to break through in Sydney for an individual gold along came 'Inky', who stunned the swimming world with eight world records in two months this year to supplant Thompson as favourite for Olympic gold in the 100m freestyle and butterfly.

Faced with such dramatic improvement from de Bruin, 27-year-old Thompson is facing up to a stern challenge in the Sydney pool to become the greatest US gold medal women's winner, an achievement she currently shares with speedskater Bonnie Blair.

"I don't feel under siege, I feel like I have a great opportunity to race great competitors and I'm looking forward to it," said Thompson.

"I think Inge's world records just present more of a challenge for me and keep me on my toes."

Thompson captured Mary T. Meagher's 18-year-old 100m butterfly world record of 57.93 seconds last year but de Bruijn has swum faster twice, including her world record of 56.64.

De Bruijn also holds the world record of 53.80 in the 100m free, a mark Thompson held from 1992 until 1994.

AFP