England was rocked by a major Covid scare ahead of day two of the third Ashes Test Monday with four members of the team camp -- two support staff and two family members -- testing positive for coronavirus.

The team and management were forced to undergo urgent rapid antigen tests just as they were about to leave their hotel for the Melbourne Cricket Ground.

They were given the all-clear barely 45 minutes before play was due to begin, with the start pushed back half an hour until 11am (0000 GMT) to give them a chance to warm-up.

"Cricket Australia has been informed that two members of the England Cricket team's support staff and two of their family members have returned a positive Covid-19 rapid antigen test," it said in a statement.

"The affected individuals are currently isolating.

"The entire playing group and all other support staff have undertaken rapid antigen tests this morning and all have tested negative," it said.

"The England Cricket team will also have PCR tests today, and both teams will take extra precautions throughout play. Both playing squads remain unchanged."

Australian broadcaster, the Seven Network, also said there had been a positive case among its staff working at the Melbourne Cricket Ground, forcing last-minute changes to their commentary team.

Australia head into day two on 61 for one in reply to England's 185 all out.

After heavy defeats in Brisbane and Adelaide, England must win in Melbourne to keep the five-Test series alive, with Australia only needing a draw to retain the urn as holders.

Australia captain Pat Cummins said the dramatic events were a sign of the times.

"It kind of feels like the last few years, doesn't it?" he told sports broadcaster SEN.

"But it's a sign of the times, you've got to be pretty flexible."

Coronavirus impacted the second Test at Adelaide with Cummins ruled out just before the start for being in close contact with a positive Covid-19 case.

Two members of the media covering the match also tested positive.