Sundowns welcomed back goalkeeper Denis Onyango while handing a start to last week's hat-trick hero Lebohang Maboe, with Ndumiso Mabena leading the front for Celtic.
The Brazilians were giving an inviting opportunity in the opening minute after Themba Zwane sliced through the defence to get goal-side, but hoofed over in the end.
Sundowns continued to assert authority five minutes to the half-hour mark as Maboe got a sight of goal from close-range, but went straight at Celtic goalkeeper Sipho Chaine.
Zwane had a golden chance to put Sundowns in front 30 minutes in from Maboe's ball to the near side of the area, but was unable to beat Chaine after making a late run in the area.
Onyango was finally given work to do after tipping Victor Letsoalo's looping header from the far side behind for a corner-kick as the half concluded.
Sundowns were rapidly out of the starting blocks five minutes after halftime and found Gaston Sirino shooting wide of the near post, while captain Hlompho Kekana went off target from range.
John Maduka's outfit on the other hand upped their momentum just after 60 minutes with the introduction of Tebogo Potsane and Neo Maema.
Kekana issued further threats shortly towards the midway quarter in the second half, but was not able to steer Lyle Lakay's delivery from a corner on target.
Sundowns did find the all-important breakthrough ten minutes to the end after Sirino darted in-wards from the left before rattling the bottom corner.
A point-blank save from Onyango in the last five minutes denied Andile Fikizolo, with Wandisile Letlabika hoofing over from a corner late on, leaving Masandawana to complete the 2019/2020 treble.
Celtic: Chaine, Letsoalo, Mahashe, Luthuli, Baloyi, Chabalala, Letlabika, Fikizolo, Phalane, Mabena, Ngobeni
Subs: Mabokgwane, Mashikinya, Lingwati, Maema, Potsane, Sera, Maloisane, Masuku, Matjila
Sundowns: Onyango, Ngcongca, Lakay, Nascimento, Madisha, Coetzee, Mkhulise, Kekana, Sirino, Zwane, Maboe.
Subs: Mweene, Makgalwa, Mkhuma, Mabunda, Arendse, Jali, Meza, Langerman, Morena.