Man of the Match Hlompho Kekana and Leonardo Castro struck either side of the break at Lucas Moripe Stadium as Downs inched a point ahead of Bidvest Wits, and extended their unbeaten run to 15 games in all competitions.
The Brazilians, who clinched Telkom Knockout honours in December, have accumulated 33 points at the half-way stage of the season.
Matsatsantsa, touted as title contenders in pre-season, are 10th in the standings with 17 points.
SuperSport started well and conjured the first chance through Dove Wome who shot wide on two minutes after being put through on goal by Jeremy Brockie.
Sundowns' first shot on target came on 14 minutes, Khama Billiat forcing Ronwen Williams into a good save from a dipping free-kick.
Billiat and Keagan Dolly were a constant menace and the latter played an integral part in the opener.
The former Ajax Cape Town winger took the shot which Williams parried for a corner-kick and then supplied the resulting cross which Kekana headed home two minutes before the interval.
Things went from bad to worse for Matsatsantsa two minutes following the break, another clumsy error pounced on by the Brazilians. The duo of Billiat and Dolly again involved, this time the Zimbabwean supplying the assist for Castro to tap in.
Williams went some way in making up for his mistake, denying Billiat on several occasions while Castro was unlucky to see his header attempt graze the outside of the post.
SuperSport showed some fighting spirit late on, but Sundowns were deserved winners on the night.