Top-order batsman Raynard van Tonder and fast bowler Lutho Sipamla have received maiden call-ups to South Africa's Test squad, while allrounder Dwaine Pretorius has been cleared fit to be a part of the group too. That takes the total number of players in preparation for the two-Test series against Sri Lanka to 19.

At least 12 of those players, including van Tonder and Sipamla, were part of domestic matches in which cases of Covid-19 were detected this week and may not be able to enter the biobubble on Saturday, which may necessitate further changes to the squad. For now, South Africa have chosen to add to their playing group rather than make any announcements about who may be unavailable and forced to self-isolate.

Van Tonder, a former national Under-19 captain, has been rewarded for his form in the domestic four-day competition, where he is on top of the run-chart. His most recent knock was a double-hundred, which set the Knights up for a big win over the Lions, Sipamla's team. That match was Sipamla's first red-ball cricket of the summer and he took 2 for 75. Also, in that fixture, one Lions player tested positive for Covid-19 on day three and was substituted, with the game allowed to continue. Testing and monitoring have continued when it comes to other Lions players.

Pretorius, who also plays for the Lions, was not involved in the match as he was recovering from a hamstring injury, which had ruled him out of the aborted white-ball series against England. He was due to play in the round of fixtures that were scheduled to start this Sunday but because the matches have been postponed, Pretorius has been added to the national squad.

"Pretorius has made great progress from the hamstring injury he picked up last month just before the start of the England tour. He would have completed the last step of the CSA Return to Play protocol by playing in the now postponed round of the 4-Day Cup and will instead work closely with the team's medical staff and coaches to ensure that he is Test match-ready," a CSA statement said.

Kagiso Rabada, the other injured player among South Africa's regular playing group, has not been cleared to play after sustaining a groin injury against England and is expected to sit out the Sri Lanka series. Rabada's absence has resulted in South Africa calling up reinforcements including Sipamla and, earlier this week, Migael Pretorius.

South Africa's players were tested for Covid-19 between Wednesday and Thursday and will be tested again on arrival in Centurion tomorrow. They will spend the first 72 hours in managed isolation in their hotel rooms with training on a one-on-one or small group basis and will be tested for a third and final time on Tuesday next week, two days before the series starts on Boxing Day.

Squad: Quinton de Kock (capt & wk), Temba Bavuma, Aiden Markram, Faf du Plessis, Beuran Hendricks, Dean Elgar, Keshav Maharaj, Lungi Ngidi, Rassie van der Dussen, Sarel Erwee, Anrich Nortje, Glenton Stuurman, Wiaan Mulder, Keegan Petersen, Kyle Verreynne, Migael Pretorius, Dwaine Pretorius, Lutho Sipamla, Raynard van Tonder