The Bombonera was scheduled to host the opening match of the two-legged final in South America's equivalent of the Champions League on Saturday.
Boca supporters began filling the stadium two hours prior to the original kick-off of 8pm UK time but the match will now take place at 7pm GMT on Sunday.
The game had been pushed back by two hours following a pitch inspection, but the game has now been officially called off due to heavy rain.
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Boca club staff worked frantically in a bid to have the game go ahead but it will now take place 24 hours later.
The rain had been falling all afternoon in the Argentine capital, and the postponement represents a major headache for the many fans around the world who will have forked out a lot of money to attend the unique occasion.
Never before have Boca and River faced off in the Copa Libertadores final, but the deluge at one of football’s great cathedrals means the only topic of conversation in the country now has an unexpected chapter.
Despite the best efforts of Boca staff, the Copa Libertadores first-leg clash was postponed
Image credit: Getty Images
Despite the sodden conditions, the River Plate team bus was greeted by swathes of home supporters at their own stadium shortly before 4pm UK time ahead of making the short trip across the city.
The second leg at River's El Monumental is scheduled for November 24, but club football is set for an international break, meaning the new date and time had to be swiftly arranged.
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