Chris Lynn, the Brisbane Heat captain, and Dan Lawrence, one of the club's overseas signings, will be physically distanced from the rest of the team and opponents in Monday night's fixture against the Sydney Thunder as Cricket Australia investigates a potential Covid-19 protocol breach by the two players in Canberra on Saturday.

Both Lynn and Lawrence have tested negative for Covid-19 since their possible breach was discovered. While still permitted to play, they will need to prepare separately from the rest of the two teams and not take part in any close huddles or celebrations over the course of the game, as they are for the time being considered to be outside the strict biosecure hub all BBL players are meant to be cocooned within for the balance of the tournament.

The possible breach relates to Lynn and Lawrence socialising together in public on Saturday night, a circumstance that is not necessarily a breach because players are permitted to dine in public, provided they are sitting outside. It is the first significant instance of CA needing to investigate a possible contravention of hub protocols, after numerous such instances in the winter football codes in Australia earlier this year.

There has been tension among some players and coaches and CA's administrators over the strictness of hub protocols for the BBL, given the low level of Covid-19 infections in the general Australian community at present, something that has also allowed state borders to re-open. However, the decision to allow Lynn and Lawrence to play also reflects how the BBL could ill-afford to lose two of its bigger names as it struggles against perceptions of a weaker than usual roster of talent.

"It is important we maintain the integrity of the bio-secure hub to ensure the safety of the public, players, staff and officials and minimise issues associated with travel between state borders during the tournament," CA's head of integrity Sean Carroll said. "While we are fortunate to live in a country with a low rate of infection compared with many other parts of the world, we are still in the midst of a global pandemic and, as we've seen on a number of occasions in Australia, COVID-19 breakouts and border closures remain a genuine risk.

"We are always monitoring the public health situation and attempting to strike the appropriate bio-security balance between keeping everyone safe on both sides of the hub and providing as much freedom as possible for those within it. We appreciate that this has been a challenging year for everyone, but we must insist on our bio-security measures being respected and followed so as not to jeopardise public health and safety or the viability of the tournament."

CA's chief medical officer, John Orchard, explained that there had already been multiple instances this summer where players have taken part in BBL practice games while not being a part of the biosecure hubs created for the tournament.

"We're confident this will be successfully achieved again tonight at Manuka Oval," Orchard said. "They must maintain a physical distance on and particularly off the field (indoors) with team-mates, opposing players, staff and match officials. We have protocols in place for all matches for interaction between those inside and outside the hub.

"Factors including the outdoor nature of the contest, the generally socially-distanced nature of cricket on-field and the fact Canberra is considered a low-risk city support the conclusion that both can play tonight without posing a meaningful risk."