Brazilian players stole the limelight with goals and an assist at King Goodwill Zwelithini Stadium on Saturday.
Arthur Sales justified Miguel Cardoso's surprise decision to start him ahead of red-hot Iqraam Rayners when he finished a defence-splitting pass from compatriot Lucas Ribeiro Costa to hand Sundowns the lead after 19 minutes.
Seven minutes into the second half, Masandawana survived a Richards Bay attack as the crossbar denied Yanela Mbuthuma who had beaten Denis Onyango with a headed effort.
Ribeiro then deflated the Natal Rich Boyz's push for an equaliser when his low shot from the edge of the box made it 2-0 for Masandawana.
It was the first time for Sundowns to win a match by more than a goal after three previous games under Cardoso were 1-0 slim victories.
Even if second-placed Orlando Pirates beat Magesi FC on Sunday, the Tshwane giants go into the New Year while at the top of the table after frustrating Richards Bay who are yet to score a goal against them in four seasons.