Despite Sundowns coach Gordon Igesund adopting an attacking approach to the game, the Brazilians failed to penetrate the hosts' defence in a dull first half at the Amaan Stadium.
The visitors pushed more men forward in the second half and were duly rewarded midway through the half when Moriri scored from corner.
Although the hosts threw everything at Sundowns, Igesund’s charges held on to secure a vital victory away from home.
However, the result came at a stiff price for the Chloorkop side, who saw Benson Mhlongo, Michael Manzini and Lungisani Ndlela all sustain injuries.
Starting Line-up: Marlin, Mere, Mhlongo, Manzini, Kannemeyer, Nyandoro, Dhladhala, Chabangu, Ndlela, Acuna, Moriri.