There was no rest for Wayde van Niekerk after he lived up to his top billing by claiming 400m gold at the world championships in London. After initially struggling with the cold, the 25-year-old ran a solid final bend to blast to victory in 43.98 seconds with a lot to spare, and went straight into recovery ahead of yesterday's 200m semi-finals, with the final today.

"It was quite freezing and I struggled to get myself warmed up and ready," said Van Niekerk, who came into the 400m as defending world and Olympic champion.

"I was doubting my momentum. In the last 150 metres I tried putting in an extra gear, but I couldn't catch my stride until my last few metres. I just allowed the race to go through to the finish line."

Thoughts will turn straight to the 200m, and a rare double. The last athlete to claim the 200/400m double was American Michael Johnson, who achieved the feat the 1995 worlds in Gothenburg, repeating the achievement a year later in the 1996 Olympics in Atlanta.

"It's easier said than done," said Van Niekerk, who smashed Johnson's 400m world record when winning gold in Rio and then his rarely-run 300m record in Ostrava last month.

"It's competition, it's very unpredictable.

"My body still feels very good. It took me a while to recover.

"But from endurance I go straight to speed... It's a day-by-day, step-by-step process for us athletes."

Van Niekerk reiterated that every season threw up new challenges.

"I know it's never going to be a walk in the park," he said. "I'm just so grateful to say I came through with a gold medal.

"Every year has its new challenges, and every year it gets tough. I don't think it ever became easier. Right after Rio I found out I had a back injury, and this entire season I have been struggling to find fitness, but at the same time my times have been getting better, especially in the short sprints."

Van Niekerk, the first athlete to break 10 seconds over 100m, 20sec over 200m and 44sec over 400m, added he was delighted his coach Anna "Tannie Ans" Botha would also receive a medal as part of a championships initiative to reward coaches.

"Everyone knows the superstar coach I have," he said of the 74-year-old great-grandmother who oversees the hottest property in world athletics.

Meanwhile, Kenya's Olympic and newly-crowned world 3,000 metres steeplechase champion, Conseslus Kipruto, said yesterday he would attempt a world record at the final Diamond League in Brussels on Sept. 1. The 22-year-old Kipruto won silver in Moscow in 2013 and in Beijing in 2015 behind compatriot Ezekiel Kemboi. He continued his country's dominance of the event with a courageous victory at the World Championships in London on Tuesday, just weeks after recovering from an ankle injury.

"Now that I have the Olympic and world titles, I think I am ripe for the world record, which I will attempt in Brussels on September 1," Kipruto told Reuters. Qatar's Kenyan-born Saif Saaeed Shaheen set the world steeplechase record of 7:53.63 on Sept. 3, 2004 at the same Van Damme Memorial event in Brussels.