Four-time Olympic gold medallist athlete Sanya Richards-Ross will be the event ambassador for the Airtel Delhi half marathon to be held on October 21. She is the fastest American woman in the history of 400m with her time of 48.70s set at the 2006 IAAF World Cup. Ross was the best 400m runner in the world for a decade, ranking No. 1 in the world from 2005-2009 and again in 2012. In addition to her Olympic accolades, she is also a 7-time medalist at the World Championships in Athletics (five of which are gold).