The match against the Vodacom Bulls on Saturday has been postponed because of a number of positive Coronavirus tests in the host side’s camp.
In addition, the Springboks’ second Test against Georgia, scheduled for on Friday, also looks set to fall by the wayside, with both teams hit by Covid.
The Lions’ second tour match, against the Sharks in Johannesburg on Wednesday evening, is still on.
South Africa is reeling from a third wave of infections in the country, raising more questions about the Lions tour.
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 against the Lions on Saturday.
Organisers are hoping the match can be rescheduled or that an alternative opponent can be found.
But a bigger threat to the Lions tour is the outbreak among the South African national squad.
The Springboks lock forward Lood de Jager tested positive for Covid-19 on Monday, forcing the other South Africa players into isolation as close contacts.
Now four more positive tests have been recorded among the Boks players - Marvin Orie, Frans Steyn, Handre Pollard and Frans Malherbe - along with six among management, including head coach Jacques Nienaber.
Meanwhile, there have been four positive results among the Georgian team.
The latest medical data from the Springbok and Georgian teams will be assessed by the Medical Advisory Group (MAG) on Wednesday morning.
“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 MAG 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.”
The Lions added in a statement: “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.”