Natalia Ishchenko and Svetlana Romashina scored 98.6 points out of a possible 100 with their near-perfect execution in a "free" routine that played on the eerie precision of the sport and drew cheers from the crowd.
Their series of syncopated, puppet-like movements, all flexed feet and sharp elbows, was set to the music of films playing on the same ghoulish theme, including Tim Burton's Sleepy Hollow.
The routine took them to a total of 196.8 points, after Sunday's technical round, topping the rankings.
China's Huang Xuechen and Liu Ou with 192.81 points were the second-highest scoring qualifiers for the final after the free routine, a sequence of the duo's own choice, combined with choreography.
Spain's Ona Carbonell Ballestero and Andrea Fuentes Fasche grabbed 192.59 points with a fluid tango-based routine, coming third out of the top 12.
Russia broke the United States and Canada's dominance of synchronised swimming over a decade ago and has since outshone its competitors in a sport that is as famous for its glittering costumes, excessive make-up and nose clips as it is for the balletic moves and acrobatics executed in a 3-metres deep pool.
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