Pat Cummins was the victim of "really, really bad luck" as Australia's captain was forced to miss the second Ashes Test and go into isolation.

That was the verdict of Cricket Australia CEO Nick Hockley, who said the team had no option but to go into the Adelaide clash against England without their new skipper.

Cummins was dining at a restaurant on Tuesday and sat nearby to someone who has since been confirmed as a positive coronavirus case.

The star paceman did not breach any biosecurity protocols and isolated as soon as he became aware of the situation. Cummins has since had a PCR test, which produced a negative result, and said he was "gutted" to be ruled out of action. Michael Neser came in for his debut, replacing Cummins.

What it means for Cummins is that he could only watch on television as Australia made a bright start against England, reaching 211-2 in 78 overs as the first day continued to unfold.

Hockley said on BT Sport: "It's certainly been eventful, and it's so disappointing that Pat was ruled out as a close contact last night

"No one's more disappointed than Pat and everyone's been working extremely hard overnight to get the facts, and ultimately it was determined, working with the health authorities, that he had been in close contact with a positive case. It's just really 'wrong time, wrong place', and it's really, really bad luck. We're thrilled that he's going to be fit and raring to go on Boxing Day.

"We worked to establish the facts. We worked closely with SA [South Australia] Health. Ultimately, if you do become a close contact then the rules are to isolate for seven days, so there was really no option in the end.

"We've got protocols in place to make sure that multiple players don't get tied up in that situation, so they have to dine in small groups. If there's one consolation, it's that everyone else is available to play."

Hockley said Cummins should be available for the next match at the Melbourne Cricket Ground, and measures were being taken to ensure he can stay fully fit.

"He's in isolation now. He's watching the cricket," Hockley said.

"We'll be putting plans in place plans to make sure that when people are in isolation they get access to the right fitness equipment, and we all want to make sure he keeps his conditioning up to a level and that he's in optimum condition for the Boxing Day Test."

Steve Smith captained Australia in the absence of Cummins as the day-night Test got under way.