Rugby fans a dashing lot in their coloured undies

Passionate rugby fans have a chance to expose their true colours today in the Undie 500 - a 500m running race for those clad in nothing but red or black underwear.

Organisers are hoping for up to 100 for the race, which starts at 12.15pm and will take place along Grandstand Rd in Auckland Domain.

The event, which will go ahead regardless of weather, is sponsored by the Newmarket Business Association and has a top prize of a $1000 voucher to any Newmarket store, plus spot prizes including a bar tab.

"We thought it was important the Lions supporters got a real appreciation of a New Zealand winter and we wanted to give them one last opportunity to prove themselves against some All Black supporters," said association general manager Cameron Brewer.

Participants and undie enthusiasts should gather at the old Domain Grandstand at noon. Access to the run is from either Park Rd or Carlton Gore Rd.

Mr Brewer said it was a great opportunity for Lions fans, fresh from their summer season, to show off their tanned bodies.

"It's undoubtedly going to be an exhibition of some of the most athletic physiques in Britain and Ireland."