Ntwari was given his chance, but his mistakes saw Petersen get back as the team's first choice.
Coach Nasreddine Nabi has since stuck with the latter since late last season, when he helped Amakhosi win the Nedbank Cup.
The 30-year-old has started the 2025/26 season well, conceding no goals in the five Premier Soccer League matches played so far.
Ntwari has not made any competitive appearance for Amakhosi this season, but he had a good game despite Rwanda's 1-0 loss against Nigeria in Group C's FIFA World Cup qualifier played on Saturday.
Amavubi coach Adel Amrouche is convinced Ntwari is among the best on the continent.