Quintero on Sunday put the hosts ahead in the 31st minute with a whistling 30-yard effort that curled into the top left corner of Gabriel Arias's goal, reports Xinhua news agency.
River were gifted their second goal just after halftime when Milton Casco's wayward shot was deflected in off Racing defender Alejandro Donatti.
Despite the result, Racing remained top of the 26-team standings, three points clear of second-placed Defensa y Justicia, who will host Argentinos Juniors on Monday. River rose to seventh spot, 14 points off the pace.
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