destroys the rest of the field to break his own world 1500m record and win his second gold medal of London 2012.
Sun finished in a time of 14 minutes 31.02 seconds - 3.12 seconds faster than the world record he set at last year's World Championships in Shanghai.
Sun was eight seconds clear of Canada's Ryan Cochrane with defending champion Oussama Mellouli of Tunisia in third.
Britain's Dan Fogg finished back in eighth.
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