Spectators will not be allowed at the Australian Open as Melbourne heads into a hard five-day lockdown announced by the Victorian government in response to the Holiday Inn Covid-19 cluster.

Victorian Premier Daniel Andrews on Friday confirmed Melbourne would be locked down from midnight. However, the Grand Slam will go ahead without fans in the stands from Saturday until Wednesday.

"The Victorian government has announced a five-day lockdown commencing at 11.59 p.m. on Friday. Australian Open sessions today and tonight will continue as planned with COVIDSafe protocols in place," Tennis Australia said in a statement.

"We are notifying ticketholders, players and staff that there will be no fans onsite at the AO for five days, commencing from Saturday 13 February," it added.

The organisers further said that full refunds would be available for anyone who has tickets for these sessions and they would be advised on how to apply as soon as possible. "The AO broadcast-only contingency plan will commence from Saturday until restrictions are lifted. Play will continue uninterrupted on the broadcast, albeit without spectators onsite," the statement read.

A cap of 30,000 fans per day -- around 50 per cent of the usual attendance figure -- had been enforced since the year's first grand slam began on Monday.

The women's final is scheduled for Saturday evening next week, and the men's decider for the Sunday.