The Brazilians survived the odd nervy moment, but never really got out of second gear as goals from Asavela Mbekile and Khama Billiat stretched their lead atop the league standings to 10 points.
Castro got the better of Phala before sending the right-back through on goal. With Williams racing off his line, the former Moroka Swallows ace showed great composure in chipping the United shot-stopper, 1-0 at the break.
This is as good as it would get for Matsatsantsa, who fell two goals behind on 75 minutes. Castro showed great determination in dispossessing Dove Wome before sending Billiat through on goal – the free-scoring attacker was never going to miss, curling the ball into the top corner.
Defeat for SuperSport sees them drop to 11th on the log standings.
In Capetown Ajax Capetown and Chippa United played to all 1-1 draw