More than 8,500 people, including 266 foreign athletes braved a chilly morning to participate in the Delhi Half Marathon today.Olympian Deriba Merga of Ethiopia defended his title in the men's category while Kenya's Marry Keitany won in the women's category.Bollywood star Shahrukh Khan and actor Rahul Bose were among the enthusiasts who took part in the top-rated running event.