This victory moves AmaTuks to 52 points, and another win on Wednesday - coupled with a Blackburn Rovers defeat - will see AmaTuks claim the title and polay in the Absa Premiership next season.
United move down to eighth with 38 points, and still have an outside chance to make the Play-offs.
A single goal from Geofrey Serunkuma in the 16th minute was enough to give Vasco da Gama the full three points against FC Cape Town. The Cape Derby did not end without drama, after Mkhanyiseli Siwahla was showed a red in the last 10 minutes of the game.
Vasco are now back in the Play-off race, in sixth place with 40 points. FC Cape Town have slipped out of the top eight, to ninth.
Blackburn Rovers lost ground in the race for an automatic promotion place, after playing to a 1-1 draw with African Warriors. Rovers remain in second with 46 points, while Warriors stay in the top eight in seventh.
The shock of the weekend was in KwaZulu-Natal, where Thanda Royal Zulu were beaten 2-0 at home by bottom half side Carara Kicks. Thanda remain in third place, but are nine points behind with three games left. Carara Kicks are on 32 points and moving away from the relegation zone.
FC AK piled more misery on Atlie FC camp, when they beat them 2-1. Atlie remain bottom of the table with 23 points, while FC AK move into the top five.
Chippa United could not cement the last Play-off position when they played to a 1-1 scoreline against relegation candidates Bay United at Philippi Stadium.
United are now level on points with FC AK, but Chippa move to fourth on goal-difference. Things are not looking good for Bay, and they are still second from bottom with 26 points, three points clear of Atlie.
Dynamos got a much needed win when they beat in-form Witbank Spurs 2-0. The win moves Dynamos to 12th place, while Spurs remain 10th.
Mpumalanga Black Aces failed to move away from the relegation zone when they were held by a 10-man Sivutsa Stars 0-0. Aces are still in the bottom three, but Sivutsa keep that two point gap between themselves and Aces.