Perth Scorchers, having lost Saturday night's qualifying final at Manuka Oval, were set to host Thursday night's semi-final at Optus Stadium.

The Scorchers' squad were slated to fly out of the nation's capital on Sunday but those plans changed when news broke of a hotel quarantine worker testing positive for COVID-19.

Cricket Australia (CA), which has largely managed to stay one step ahead of border closures while doing everything possible to ensure players avoid coronavirus hotspots, quickly decided to change its plans.

WA chief health officer Andy Robertson flagged on Sunday that Perth could potentially host the BBL final without a crowd.

But CA, one day after giving the green light for the Scorchers to return home, opted to shift Thursday's high-stakes clash to Manuka Oval.

BBL boss Alistair Dobson thanked the Scorchers "for their understanding" regarding the shift.

"This has been an unprecedented ... BBL season and the ongoing flexibility and cooperation has been vital in getting us to this point of the finals series," Dobson said.

Perth will play the winner of Sunday night's elimination final between Sydney Thunder and Brisbane Heat.

The latest development came after Perth captain Ashton Turner expressed hope that quarantine exemptions could be forthcoming for his team.

If the Scorchers are able to book a rematch against Sydney Sixers then the three-time champions will be required to visit Sydney for Saturday's SCG final.

WA had eased restrictions on travellers from Victoria and Queensland but anybody coming from NSW is required to self-quarantine for 14 days.

Such arrangements would be a bitter blow for WA and Perth coach Adam Voges, whose charges are scheduled to start their one-day campaign on February 16.

Turner, who is among the group of Scorchers heading to New Zealand after the BBL for Australia's Twenty20 tour, noted his squad is always hopeful about exemptions.

"That's a lot of the reason we're in such strict bubbles at the moment, to give ourselves the best opportunity to get exemptions," Turner said before Perth's lockdown announcement.

"Quarantine sucks. There's no two ways about it, nobody wants to do it.

"We've done a couple of stints so far. Some guys have done more than others.

"We had opportunities to win games of cricket and we haven't been good enough to do that. So we have to bear that (quarantine)."

WA's squad delayed their departure out of Adelaide after the Sheffield Shield hub earlier this season, waiting for the border to open.

They returned home then were ordered to quarantine because of Adelaide's COVID-19 outbreak.

Australian Associated Press