South Africa are allocated two Champions League places and one seems certain to be filled by runaway leaders Mamelodi Sundowns, who need nine points from nine matches to win the title.
That leaves Stellenbosch and Pirates as the chief contenders for second spot and the Cape outfit play four of their upcoming six fixtures at home.
“We fought fire with fire tonight, dug deep and showed tremendous character,” said coach Steve Barker as Stellenbosch extended an unbeaten run in all competitions to 23 matches.
“It was a massive performance at the end of a week in which we played two top-six clubs away and collected four points.
“I told my boys at half-time to up the intensity and they did. Given the strength of Galaxy at home I would have settled for a point, so to get all three is fantastic.”
Sixth-placed Galaxy went ahead on 41 minutes through Lehlohonolo Mojela, who took advantage of a slip by Fawaaz Basadien to fire across goalkeeper Sage Stephens into the far corner.
Basadien atoned after 53 minutes by equalising with a low shot and De Jong struck on 61 minutes from close range after Rwanda goalkeeper Fiacre Ntwari failed to hold the ball after a corner.
While Stellenbosch are heading toward their best league finish, fallen giants Kaizer Chiefs slumped to 10th after losing 1-0 at second-last Richards Bay in Durban.
A glancing header from captain Simphiwe Mcineka on 64 minutes separated the teams in a match Chiefs dominated only to be constantly foiled by Uganda goalkeeper Salim Magoola.
It was the 10th league loss of the season for Chiefs, who have won a record 53 domestic trophies and never finished lower than ninth in the Premiership.
© Agence France-Presse
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