Heidi Klum feels under pressure to ''outdo'' herself with her new Halloween outfit.

The 46-year-old model is currently preparing for her Halloween bash in New York City, and as the event draws closer, Heidi is becoming increasingly anxious about her outfit.

Heidi - who has staged a party every year for the last 20 years - shared: ''I'm gonna do something very, very special.

''I'm trying to do something very special on that day, because it's 20 years already. I can't believe it! 20 years ago, I thought, 'There is no real cool party in New York City and someone has to do this.' And so I did.''

Heidi hopes she'll continue to stage the bash for the next 20 years.

She told 'Entertainment Tonight': ''Why not [do it another 20 years]? Why stop the fun when you get older? I think we should have more fun when we get older!''

Heidi has worn a number of eye-catching outfits over the years, including dressing as Jessica Rabbit and as Princess Fiona from the 'Shrek' movies.

And the blonde beauty feels under pressure to outdo herself again this year.

She said: ''I'm pressuring myself. It's not the outside world, it's really me. I want to outdo myself every year again.''

However, Heidi insisted she cannot rehearse for her party.

The model - who married musician Tom Kaulitz earlier this year - explained: ''Sometimes I sit there for 10 to 12 hours. When I turned myself into a really old woman, it took like, 12 hours, so you don't really rehearse any of this stuff.

''You do it on the day and you hope that it works out. So far it always did, but you never know. Fingers and toes crossed!''