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Video - Russian pair are a perfect 10
Russian duo Anastasia Davydova and Anastasia Ermakova defended their synchronised swimming duet title with a dominant display in Beijing.
The four-time world champions earned an overall score of 99.251 - the sum of the final free and technical routines.
Davydova and Ermakova were awarded five perfect 10s for technical merit in their final duet performance.
Spain's Gemma Mengual and Andrea Fuentes won silver with Japan's Saho Harada and Emiko Suzuki taking bronze.
Those three pairs ended the first day of competition in the same order and held onto those places until the medals were decided.
Davydova and Ermakova were always going to be tough to topple from top spot as they are undefeated at major championships since 2001.
The pair are now set to join the rest of the Russian squad for the defence of their team title which begins on Friday.
British pair Jenna Randall and Olivia Allison did not qualify for the duet final after finishing in 14th place in the two preliminary rounds.
"Top 16 was our aim and we've bettered that with 14th - that's an amazing achievement," said Randall.
"These Games were all about experience and we now face a very intense and important four years going into London."