The British and Irish Lions intend to play the Sharks,who they beat 54-7 on wednesday, again on Saturday after their original opposition pulled out of the game after positive Covid-19 tests.
The Lions have two cases, but put out a winning makeshift side in midweek.
The tourists will take more Covid tests on Thursday and Friday.
"The results of those tests will determine whether we will be able fulfil this fixture, but, as it stands, we are optimistic," said the Lions managing director Ben Calveley.
"The choice of the Cell C Sharks was dictated by the fact that they have been in a bubble, have returned negative tests throughout and were prepared to take on the fixture," said SA Rugby chief Jurie Roux.
"No other team in the country could meet those conditions right now - without going into a five-day lockdown. It is not an ideal situation, but Covid-19 has made sure that we do not live in an ideal world."
The Sharks will be without their Springbok stars such as Siya Kolisi and Makazole Mapimpi for the match.
South Africa's preparations for the three-Test series, which begins on 24 July, have also been disrupted with 12 Covid cases in the world champion's camp causing their planned test against Georgia.
"We remain committed to the Tour in South Africa and determined to rise to the challenges created by the Covid-19 pandemic," added Calveley.