Elias Pelembe scored the winner early on as the Brazilians dominated proceedings against an Aces team devoid of five regulars owing to suspension and loan agreements.
Sundowns came flying out for the blocks and dominated for most of the first half.
Surprise Moriri had a chance after just two minutes when he was played in, but a poor first touch allowed Jackson Mabokgwane to rush out and thwart the danger.
Thabo Nthethe had a free header which the goalie saved at the second attempt soon after, but the goal did come on eight minutes.
Some good build-up play saw the ball find Tebogo Langerman on the left, and his cross was perfect for Pelembe, who made no mistake with the header.
There was insult added to injury soon afterwards when Mabokgwane was forced off with an ankle injury, to be replaced by eventual Man of the Match Bafana Nhlapo.
Sundowns continued to push forward but found the replacement in fine form. He first denied Teko Modise’s rocket with a one-handed save, before Nthethe’s header from the resultant corner was cleared off the line.
Modise then had a free-kick rattle the crossbar before Aces had their first shot at target, a wayward effort from Sandile Zuke on 34 minutes.
But for all the Sundowns pressure, it was Aces who almost scored just before the break. Mabhuti Khenyeza flicked the ball to Clifford Ngobeni, but Kennedy Mweene produced a world-class save down to his right to keep the lead intact.
The Brazilians continued to press after the break as Dove Wome and Hlompo Kekena came close with free-kicks, while Schut had his header cleared off the line by Thabang Rooi.
Nhlapo them came up with more magic to deny Rodney Ramagalela a wonder-goal, before saving a point-blank header from Schut.
However, it could all have ended in tears for Downs when a rare lapse at the back allowed Eddie Ngalo a free header on the six-yard box, but the effort went inches over.
So it is as you were in the standing, with Sundowns leading Chiefs by three points, but with the latter having a game in hand.