Russian favorites Natalia Ishchenko and Svetlana Romashina won the synchronized swimming duets Tuesday after the free routine final.
Silver and bronze went to Spain and China in that order, but were separated by far less than a point.
Ishchenko and Romashina stood atop the standings after all three days of the competition.
Their 98.90 score in the free routine final gave them 197.10 points overall, 4.2 more than Spain's Ona Carbonell Ballestero and Andrea Fuentes Fache.
The Chinese pair of Huang Xuechen and Liu Ou finished just .03 points further back.
Russia captured the first synchronized swimming event of the London Olympics after sweeping the sport in the last three games by winning every gold in the team and duets competition since 2000.
The team competition starts Thursday, but the United States won't be involved. For the first time ever, Americans didn't qualify a team for competition.
The U.S. was represented in duets by Mary Killman and Mariya Koroleva, who came in 11th out of the 12 pairs that qualified for the final.
Canada's Marie-Pier Boudreau Gagnon and Elise Marcotte finished fourth, 3.75 points behind the Chinese.