Sundowns started positively, as Gaston Sirino found space on the left side turned a defender with the aim to curl into the top corner but the effort glided wide.
The Brazilians continued stamping their authority near the half-way point, but there was to be a few scary moments from the Amakhosi too.
A troublesome Khama Billiat forced his former teammates to be on their toes after his runs off the ball caused lots of havoc in around the penalty area.
The amount of clear-cut chances were non-existent throughout the first spell, with the amount of passes through the final third lacking the right ingredients to wreak danger.
A coming-together between Billiat and Kennedy Mweene forced the Sundowns goalkeeper to rush off his line to prevent him from flicking the ball around him 10 minutes to the break.
A quick counterattack by Chiefs involving Siphiwe Tshabalala set-up Billiat for a tap-in but Mweene’s outstretched leg denied him his first goal for the club closer to halftime.
Downs had the first laugh early on in the second half after Anthony Laffor tricked Daniel Cardoso to race ahead and struck the post which rebounded perfectly for Jeremy Brockie who tapped in easily.
Chiefs were pegged back and needed something out of the ordinary to come back. An attempted volley from Castro yielded no positive results in spite of taking the ball off the defender but shot tamely at goal.
The pressing for much of the second half came from Chiefs, but Downs posed few dangers on the counter but the finishing from the likes of Laffor was not up to scratch.
Substitute Themba Zwane combined with George Lebese on the edge of the box and beat Itumeleng Khune with a top corner finish in added time.
Bernard Parker pulled one back for the Amakhosi after heading home a corner later on, but it was nothing more than a consolation as Downs walked away triumphantly.
Chiefs: Khune, Mphahlele, Cardoso, Mathoho, Mirwa Katsande, Ekstein, Tshabalala, Billiat, Castro Paez.
Subs: Vries, Bvuma, Petersen, Moleko, Hadebe, Ngezana, Zulu, Mahlasela, Jayiya, Molangoane, Parker, Moon.
Sundowns: Mweene, Morena, Lakay, Bangaly, Madisha, Mohomi, Mkhulise, Manyisa, Brockie, Sirino, Laffor.
Subs: Ngobeni, Silva, Arendse, Zulu, Malajila, Otladisa, Sekotlong, Ngcongca, Lebese.