Onyango will be expected to play a pivotal role for the 2016 club champions.
Former Uganda Cranes' captain and Mamelodi Sundowns goalkeeper Dennis Onyango made a third appearance in goal this season as his side claimed a 3-2 win over Jamal Salim's Richards Bay FC on Tuesday evening in the Nedbank Cup.
The Brazilians booked a spot in the round of 16 courtesy of a brace from Namibian forward Peter Shalulile and a header from center back Musa Lebusa.
Nkanyiso Zungu and Kahtleho Makateng scored for the visitors, both penalties.
The victory was Sundowns' 16th straight win across all competitions and with the CAF champions league on the horizon.
Onyango will be expected to play a pivotal role for the 2016 club champions.
Sundowns are pooled in group B along with Al Hilal (Sudan), Cotton Sport (Cameroon) and Al Ahly (Egypt). Their first group game is a home tie against Al Hilal.