A day after 14-time French Open champion Nadal was heavily beaten by Novak Djokovic in the singles, the veteran bounced back with a commanding display alongside his compatriot.
The Spanish duo, dubbed 'Nadalcraz', delighted a packed and vociferous crowd on a sweltering Court Suzanne Lenglen arena as they combined their formidable firepower to keep their gold medal dream on course.
Alcaraz pummelled a forehand winner to get the crucial break of serve in the first set with Nadal roaring his approval.
Koolhof, a former doubles world number one, and Griekspoor provided stiff resistance in the second set before dominating a second-set tiebreak, winning it 7-2.
But Nadalcaraz caught fire in the deciding third set, fist-pumping and roaring after a succession of electrifying winners as they blazed to victory.
