Pop star Delta Goodrem has pulled out of singing the Australian national anthem at today’s Australian Grand Prix in Melbourne.

Goodrem pulled out just after midday, telling race officials she had a sore throat.

Organisers are now trying to find a replacement to sing them anthem, ahead of the race’s start at 5pm.

After three days of poor crowds, there has been a big rush at the gates at Albert Park this morning ahead of the world’s first twilight Grand Prix.

Brawn GP driver Jenson Button has firmed into a $2.20 favourite, after claiming pole position in yesterday’s final qualifying session.