By the 30 km ( 1 : 47 : 54 ) mark the defending champion took charge of the race , leaving Kim more than 500 metres behind .
Heo lagging some two kilometres back .
By the 30 km ( 1 : 47 : 54 ) mark the defending champion took charge of the race , leaving Kim more than 500 metres behind and Heo lagging some two kilometres back .