Denmark's Pederson had set a world record of 2:19.11 minutes in the semi-final, breaking Rebecca Soni's previous best of 2:19.59 mins Friday, reports Xinhua.
In the final, the Dane looked as if she was going to live up to expectations as she went straight into the lead and she was in front for the first three laps.
However, Efimova launched a powerful attack at the start of the last straight and beat Pedersen in the closing meters to take the gold medal with a time of 2:19.41 mins.
It may have only been the second fastest time in history, but it was worth a gold medal and saw Efimova go one better than the silver she won in 2011.
--IANS (Posted on 03-08-2013)