After a goalless first leg in Angola, Sundowns took the lead in the home leg through Tashreeq Matthews, but Wiliete equalised early in the second period through Mabululu.
Sundowns missed several chances after that and had a goal from Brayan León disallowed as they failed to find the second goal they needed and missed out on the group stage for the first time since 2015.
It is not quite the earliest a defending champion has exited after Ghanaian outfit Hearts of Oak lost in the first round to Étoile du Congo in 2001, having lifted the trophy the year before.
Coach Miguel Cardoso recently signed a new contract to keep him at the club until 2028, but this is a massive failure given the ambition and money that have been invested by the club.
There were no such issues for Orlando Pirates as they swept to a 4-0 win over Namibian side African Stars to take the tie 5-0 on aggregate.
Evidence Makgopa scored twice to go with goals from Thapelo Mokobodi and Mpho Padime.
They now remain South Africa’s only hope in the CAF Champions League, while Durban City are the lone representatives remaining in the CAF Confederation Cup after Kaizer Chiefs were knocked out by Red Arrows of Zambia on Friday.
That was part of a hugely disappointing night for South African football in African club competition.