Naomi Watts in Sydney for Kidman Wedding

By Stephen M. Silverman

06/21/2006 at 08:30 AM EDT

Nicole Kidman's longtime friend, Naomi Watts, landed in Sydney from New York City early Wednesday to be with the bride-to-be, the Associated Press reports.

"I'm very excited for my friend," Watts, 37, told reporters, but said she wasn't "at liberty to discuss" any details of the upcoming nuptials.

Kidman, 39, and Keith Urban, 38, are expected to tie the knot this weekend at a lavish ceremony that will reportedly include guests Russell Crowe, Hugh Jackman, Rupert Murdoch and his wife Wendi Deng and Murdoch's Sydney-based son Lachlan and his wife, model Sarah O'Hare.

Kidman's two children with former husband Tom Cruise – Isabella, 13, and Connor, 11 – will fly to Sydney later this week, according to local press reports.

Watts – who was born in Britain but raised in Australia – met Kidman when they were young actresses Down Under. Sydney news outlets are reporting that she is expected to attend a bachelorette party for Kidman later Wednesday at the $3 million mansion of Kidman's sister, Antonia.

On Tuesday, Kidman celebrated her 39th birthday with a low-key dinner at her parents' home in the Sydney suburb of Greenwich. Kidman and Urban arrived in a black Aston Martin and were greeted by a handful of fans.

Earlier that day, Kidman briefly posed for pictures outside her home after reporters and photographers sang "Happy Birthday" over the intercom. She later sent bottles of water and a case of beer out to the gathered media with a note reading, "Enjoy! Nicole & Keith."

Kidman and Urban are reportedly staying in separate residences until the wedding, she in her harborside house and Urban in a downtown hotel.