South Africa face a potential selection headache, with 10 members of their 16-man squad to play Sri Lanka involved in domestic first-class matches in which positive cases of Covid-19 have been detected.

Rassie van der Dussen, Beuran Hendricks, Wiaan Mulder (all Lions), Migael Pretorius (Knights), Aiden Markram, Dean Elgar, Lungi Ngidi (all Titans), Keshav Maharaj, Sarel Erwee and Keegan Petersen (all Dolphins) were part of fixtures between the Titans and the Dolphins, and between the Lions and the Knights, in which at least five positive tests have been returned. It is not yet known which, if any, of the 10 are infected or are deemed close contacts of those who are infected. If any of them fall into these two categories they will need to isolate for 10 days from December 16.

The first Test against Sri Lanka starts on December 26 and only Quinton de Kock, Faf du Plessis, Temba Bavuma, Anrich Nortje, Kyle Verreynne and Glenton Stuurman are confirmed as available. De Kock, du Plessis, Bavuma and Nortje did not play in this round and Verreynne and Stuurman played in the Cobras-Warriors match, which was unaffected by the virus.

The latest round of domestic first-class matches saw the first franchise cricket match called off because of Covid-19 in South Africa. The top of the table clash, between the Titans and the Dolphins, was abandoned after the first day when a Dolphins player tested positive. At least three more players from that franchise have also been infected.

In the second match, between the Lions and the Knights, a Lions player tested positive on day three and was withdrawn from the match but play continued. An insider confirmed that the reason that fixture was not abandoned was on the advice of a risk assessment and because the Knights players indicated their willingness to continue.

Players from all four franchises are now being monitored and those who are deemed close contacts to the positive cases will be forced to isolate for 10 days. That means they will only come out of quarantine on December 26, on the first day of the Boxing Day Test, and will therefore not be available for selection. Those players could then be added to the bubble ahead of the New Year's Test, provided they have clean bills of health. Those who enter the bubble will be tested on Saturday, next Monday and next Wednesday, with the first Test to start on Thursday.

ESPNcricinfo understands that the biosecure bubble at the Irene Country Club - which is the venue that will host both South Africa and Sri Lanka for the two Tests - is on track and Cricket South Africa expect the series to go ahead, albeit with some absentees. Sri Lanka named a full-strength squad, barring the injured Angelo Mathews, on Thursday and will leave for South Africa on Friday. They may find their hosts severely depleted, depending on how many of their 16-man squad have to isolate following the latest Covid-19 outbreak.

South Africa is officially in its second wave of the Covid-19 pandemic and has seen a massive increase in its infection rate in the last two weeks. On Wednesday, the country recorded more than 10,000 cases for the first time since August 1 and further restrictions have been put in place, including a curfew and limits on the number of people at gatherings. The Gauteng province, where the Sri Lanka series will be played, is one of four areas in the country where the spike in cases has been deemed concerning.

Sri Lanka are due to be South Africa's second international visitors this summer, after England who withdrew from their tour last week. England played three T20s but the three scheduled ODIs were postponed after three South African players and two hotel staff tested positive for Covid.

Two England players also tested positive but on verification, their results were confirmed negative. England's bubble was more lenient than Sri Lanka's will be, after the English players requested recreational activities including golf. They played at five different courses on eight occasions while in South Africa.

Firdose Moonda is ESPNcricinfo's South Africa correspondent