With genuine chances during the encounter far from plentiful, it was The Brazilians who dominated possession and territory and ultimately converted two of their few opportunities to wrestle the win.
Keagan Dolly struck midway through the first period, and then completed his brace deep in second half injury time to wrap up the contest.
The first shot on target for either side fell to Jomo Cosmos in the 17th minute. Running into the area at pace Brice Aka reeled off a sharp strike, but Sundowns keeper Dennis Onyango was alert to the danger as he made the save.
With their first real chance of the encounter, Sundowns were ruthless in taking the lead in the 22nd minute. Themba Zwane whipped in a cross for Dolly whose header had the beating of Cosmos keeper Sherwyn Naicker to make it 1-0 to the visitors.
On the whole, Sundowns would have been pleased to head to break with the advantage as their chances on goal were few in number.
Three minutes after half-time, Sundowns began tearing apart the Cosmos defence as a goalmouth scuffle saw Naicker forced into a double save with the second attempt coming from close range from Katlego Mashego.
