South Africa's Wayde van Niekerk has set a new personal best to claim the gold medal in the men's 400m final at the World Athletics Championships in Beijing.

Van Niekerk crossed the line at 43.48s after bursting clear of the field in the opening 250m, forcing defending champion LaShawn Merritt of the USA to settle for the silver, despite also running a personal best.

Olympic champion Kirani James of Grenada finished strongly with his best time this season, but was unable to overhaul the two leaders in the final metres, picking up the bronze, with all three medallists running sub-44 seconds for the first time in the history of the event.

Great Britain's Rabah Yousif finished sixth in a time of 44.68s.