Chiefs netted through former Masandawana players Leonardo Castro (hat-trick) and Khama Billiat, while Jose Meza and Gasro Sirino scored for Sundowns
Ernst Middendorp unleashed an experienced team as Amakhosi looked to clinch the one-day competition for the first time.
Middendorp’s counterpart Pitso Mosimane named a team made up mostly of fringe players as the Brazilian looked to defend the unofficial trophy.
Chiefs dominated the match from start with Khama Billiat and Leonardo Castro causing havoc for the Sundowns defence with their clever runs in the final third.
It took only eight minutes for Castro to haunt his former side as he scored with a neat finish to make it 1-0 to Chiefs after Billiat’s initial shot had hit the upright.
Sundowns tried to push for the equalizing goal, but Nigeria international Daniel Akpeyi was in top form in the Chiefs goal-posts as he denied Lyle Lakay with a great save.
Chiefs were soon 2-0 up when Castro scored with a close-range finish – beating Sundowns goalkeeper Reyaad Pieterse for the second time on the half-hour mark.
The momentum was with Amakhosi with the half-time break approaching and Castro completed his hat-trick with a header to make it 3-0 in the 44th minute.
Chiefs were running rampant and they managed to extend their lead on the stroke of half-time when Castro set-up Billiat, who beat Pieterse to make it 4-0 heading into the break.
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The Tshwane giants played a lot better in the second half with Mosimane having introduced Jose Meza at the interval.
The Venezuelan attacker did make an impact as he beat Akpeyi from close range with a decent finish to make it 4-1 to Sundowns on the hour mark.
Meza was looking lively for the reigning PSL champions as his effort from a tight angle narrowly missed the target with the Amakhosi defence exposed.
Sundowns were awarded a late penalty after Akpeyi fouled Tebogo Langerman in the box and Gaston Sirino converted the resultant spot-kick to make it 4-2 in stoppage time.
Chiefs then stood firm at the back and ultimately, they clinched the Shell Helix Ultra Cup for the first time after defeating Sundowns 4-2 on the day.
Sundowns will be looking to avenge the defeat when they host Chefs in a PSL match at Loftus Versfeld Stadium on Sunday, October 27.