A 500-case jump in new daily COVID-19 cases in Victoria is being blamed on AFL grand final long weekend gatherings.
The state saw a surge in cases on Thursday, 1438 new locally acquired cases up from 950 on Wednesday.
There are 11,018 active cases in Victoria and the five more deaths announced on Thursday takes the current outbreak's toll to 41.
"This is more than a 50 per cent increase on yesterday's daily numbers and I'm sure that will be of great concern to all Victorians," Premier Daniel Andrews said.
"We were very clear those numbers would go up. They go up faster, of course, if people don't follow the rules."
He again urged Victorians to stop visiting each other in their homes and breaching public health orders.
"Given what we know from interviews over recent days, many of these cases were completely avoidable," Mr Andrews said.
Authorities believe at least 500 of Thursday's cases are linked to AFL gatherings across Melbourne.
"The contact tracers tell us that there are significant numbers of social gatherings on Friday and Saturday over a long weekend," COVID-19 Commander Jeroen Weimar told reporters.
"Grand final parties, other social gatherings, barbecues, backyard visits, all of this generating significant and additional case loads.
"We know that everyone's fatigued. We know everyone's tired of this. But today is a significant setback in how we manage this outbreak."
He urged anyone who went to any gathering at the weekend to get tested, whether their companions were displaying symptoms or not.
The profile of cases was also changing, Mr Weimar said, skewing higher towards men aged in their 20s, 30s and 40s.
About six-in-10 cases are in new households.
If Thursday's case number jump becomes a trend, Victoria will go from being just below the case projections done by the Burnet Institute - which is guiding the state's road out of lockdown - to being in the worst scenario, Mr Weimar says.
Opposition Leader Matthew Guy said the premier needed to stop blaming other people and ordinary Victorians for the pandemic's spread.
"We all knew this moment would come. We all knew we would be opening back up. We all knew there would be more cases, sadly," he told reporters.
The government should have been spending the past 18 months better preparing the health system for this inevitable increase, Mr Guy said.
Mr Andrews said the state would continue with its plan to get out of lockdown, but there may need to be a pause if numbers reach an unsustainable level before October 26, when 70 per cent of the eligible population is expected to be fully vaccinated.
To help bring that target and the 80 per cent fully-vaccinated benchmark forward, the time between Pfizer vaccine doses will be halved to three weeks in Victoria.
The interval change kicks in from October 4, so anyone who has received their first Pfizer dose will be able to bring forward their second.
The vaccine booking system will be updated overnight on October 3.
There will also be a shift in 88,000 Moderna vaccines from community pharmacies to state clinics to hasten the rollout, with pharmacists struggling to cope with the sudden demand.
For exposure sites visit www.coronavirus.vic.gov.au/exposure-sites