Carolina Kluft insists she's not invincible and expects a tough battle at the World Championships in Japan.

The Swedish sensation has simply been unstoppable in the heptathlon since clinching her first gold at the 2002 European Championships and has yet to be defeated in any multi-discipline event since March of that year.

Kluft has gone on to win two world titles, another European crown and most importantly the Athens Olympics in 2004 - but there's still plenty more to come from this fierce competitor.

Indeed the way she's comfortably dominated the heptathlon in recent years has led many to describe her as invincible, while others believe she could feasibly win every possible gold until the day she retires.

Still only 24, that time is still long in the distance but Kluft certainly admits her rivals are capable of causing an upset.

She told sportinglife.com: "I've never said anything about being invincible - I'm definitely not. It's the journalists who say all that. I don't fear anything because competition is competition and nobody is unbeatable.

"I expect to do as good as I can before I get onto the track. The place I have at the end I'll have to accept because I can't do anything about my competitors."

Kluft's major challenge in Osaka will come from Lyudmila Blonska of Ukraine, who finished second behind her in Gotzis before going on to set the world's best score this year of 6,733 points in Kiev on August 4.

However, suuch statistics don't worry Kluft and she added: "Everyone starts on zero so it doesn't matter about previous records or how many medals they have. Anyone can win what should be a tight competition."

Great Britain will be represented by Olympic bronze medallist Kelly Sotherton and the in-form Jessica Ennis - both of whom Kluft feels have a decent chance of mounting a significant challenge.

She said: "They're great athletes so they will probably give me a very good competition, I hope."

Sotherton, of course, has all too frequently been troubled by the javelin event but Kluft admits she's not the only one, adding: "I've had problems with the javelin this year - it's a very hard event with lots of technique to master."