The South African had been tipped ahead of the championships to do the unthinkable and once again threaten the sub-43-second barrier but on a chilly night in East London the conditions didn't allow for it.
Seemingly with one eye on the shorter distance, van Niekerk ran hard over the first 300 metres and opened up a four-metre lead which he held, cruising over the line in 43.98 ahead of Bahamian Steven Gardiner.
"I've got a good team who will help me recover well for the 200m and I'm looking forward to that," Van Niekerk said.
Pierre-Ambroise Bosse produced the biggest surprise of the world championships so far when he clinched France their first ever global gold in the men’s 800m.
The 25-year-old Bosse hit the front down the back straight and dominated the later stages of the race for France’s first gold of the championships, clocking 1:44.67 seconds. It was the first European victory in the event since 2001.
The Frenchman said: “It felt like a nightmare as I was getting chased. I could not understand why nobody was going past me. Even when I crossed the line I could not believe it. The others killed themselves and they were already dead in the last 100m. I was like a witch casting a spell on them.”
Within minutes of Bosse’s victory, Renaud Lavillenie took the bronze in the men’s pole vault for France in a competition won by an extremely composed Sam Kendricks, wjile Poland’s Piotr Lisek claimed silver.
Kenya’s Olympic champion Conseslus Kipruto produced a home straight celebration more akin to a goal celebration at the football matches that West Ham play in the London Stadium as he won the 3000m steeplechase final in 8:14.12.
Even with Morocco’s silver medallist Soufiane Elbakkali close behind, Kipruto put his hands up behind his ears with 30 metres to go, as if to ask the crowd for more noise to celebrate another victory for Kenya in an event they have dominated for decades. American Evan Jager, who had led for most of the race, held on for the bronze.
Czech Barbora Spotakova, who won the Olympic title in the same London Stadium in 2012, rolled back the years with her first world title for 10 years at the age of 36. A throw of 66.76m sealed the victory over Chinese medallists Li Lingwei and Lyu Huihui.