Olympic champion Jodie Henry's coach believes the women's 100 metres freestyle final at the world championships will be the fastest in history, with six genuine contenders.

Henry's coach Shannon Rollason predicted the unprecedented level of competition could lead to the world record falling, but said it could also lead to costly mistakes being made.

"When that can happen there's got to be every likelihood that there's going to be a world record. It's going to be a fantastic race to watch."

Until last year, sub-54 second pace was the domain of reigning world and Olympic champion Henry and her compatriots Libby Lenton, who beat Henry for gold at last year's Commonwealth Games, and Alice Mills.

By the end of 2005, the only non-Australian women to have achieved the feat were retired Dutchwoman Inge De Bruijn and American Natalie Coughlin, who notched 53.99 in 2002.

Among the new members of the club is German Britta Steffen, whose 53.30 second swim at the European championships in August bettered Lenton's 53.42 second world record time from the Commonwealth Games trials in January.

Rollason said Henry had been performing well in training, but the pressure of the high-class field created an unpredictable element to the race.

"It's all about racing and being able to race under the pressure of a world championships and race in a field where six girls have been under 53 seconds," he said.

"They're all used to swimming in finals where everyone can swim 54 seconds, so that's going to heighten things and when that kind of atmosphere's been heightened people can make mistakes.

But both Rollason and Lenton's coach Stephan Widmer welcomed the challenge, saying the Australians would be spurred on to better things, with Widmer describing it as a "wake-up call".

"When I see results from (international competitors) I post it on the board at the pool, then the girls walk over there and go `ooh, aah', you get some little comments about it," Widmer said.

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