Themba ‘Mshishi’ Zwane scored a brace as Onyango and Mamelodi Sundowns cruised past CR Belouizdad.
The two sides clashed at the National Stadium in Dar es Salaam, Tanzania, on Sunday.
The Algerian champions had to play most of the match with a man down.
This was after Chouhaib Keddad was shown a straight red card just three minutes into the match.
He deliberately handled Zwane’s goal bound shot.
Onyango and Mamelodi in control
Sundowns went a goal up with Zwane scoring from the penalty spot.
The Algerians equalized a minute to half time through Amir Sayoud.
But Sundowns cleaned up the game in the second half with Zwane, Peter Shalulile, Lebohang Maboe and substitute Kermit Erasmus scoring.
Dennis Onyango was kept busy in the Sundowns goal.
He had to do well to save a Youcef Bechou effort from the left after he raced to a through ball.
Denis Onyango however had to be substituted before the second half started.
He appeared to have picked up an ankle injury and in his place came Zambian Kennedy Mweene.
The victory makes it two victories in a row for the 2016 champions who have now gone to six points.
They opened a four-point buffer between them and second placed TP Mazembe on top of Group B.