The only goal of the match came in the 59th minute as Masandawana captain Hlompho Kekana capitalised on a poor back pass to round the USM goalkeeper and slot into an empty net.
The result leaves Sundowns on top of Group C with seven points from three games, two ahead of Wydad Casablanca, who thumped Angola’s Petro de Luanda 4-1 on Saturday.
Sundowns’ next Champions League game is at home to USM Alger on January 11, where a win will seal there place in the quarterfinals, as long as Petro do not beat Wydad in Angola.
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