The British & Irish Lions' third tour game on Sunday against the Bulls in Pretoria has been postponed after several positive COVID-19 cases in the ranks of the South African team.
It is also likely that South Africa's warm-up test against Georgia, to be played in Johannesburg on Friday, will also be called off after positive test results in both camps, as a third wave of coronavirus cases engulfs the country.
"The Lions' match against the Bulls has been postponed with a view to rescheduling or to accommodate an alternative opponent, while the Springboks' second Test against Georgia is also being reviewed," said a joint statement from SA Rugby and the Lions.
The Lions' second tour match against the Sharks in Johannesburg tomorrow morning, however, is still going ahead.
"Four Bulls players and one member of management returned positive tests which, in combination with their close contacts, made it impossible for them to field a team, according to the tour safety protocols," added the statement.
The game might yet go ahead later in the tour because regulations make provision for additional midweek matches to be added if there is agreement between all parties.
Four positive results in the Georgia team and four additional positive tests by Springbok players (Marvin Orie, Frans Steyn, Handre Pollard and Frans Malherbe) plus six among management, including coach Jacques Nienaber, have further complicated planning.
The latest medical data from the Springbok and Georgia teams will be assessed by the tour's Medical Advisory Group today.
"These positive results are a setback and have underlined the danger of transmissibility of the delta variant," said Jurie Roux, CEO of SA Rugby.
"The Springboks' second Test against Georgia is now in serious doubt, but we will wait for the advisory group to consider the data and we will make the final decision tomorrow.
"The priority is to maintain the integrity of the test series and we will continue to focus on that," he said.
A further update will be issued on potential alternative opponents for the Lions and on the Springboks' second Test against Georgia as soon as the positions are finalised, the statement said.
South Africa hit a record of 26,000 daily COVID-19 cases at the weekend as its total death toll moved above 62,000.
The country is in a severe lockdown after a third wave of cases have stretched hospitals and staff.