Lausanne - World record holder Wayde van Niekerk will return to the 400 metres at the Diamond League meeting in Lausanne on Thursday, after starting the season focusing on the shorter events.
The 24-year-old, having run personal bests in the 100m (9.94sec) and 200m (19.84sec) last month, set a new world best time of 30.81sec in the rarely-run 300m in Ostrava last week, beating a long-time record held by Michael Johnson.
But now van Niekerk is ready to turn his attentions back to the distance in which he is also the reigning world and Olympic champion, having run the world-record time of 43.03sec in Rio de Janeiro last August.
"I definitely know that I'm in good shape in every single distance below 400m, except the 400," the South African told a press conference on Wednesday.
"It's about continuing this really good form that I've been building and improving both my 200 and 400m times.
"I'm glad that I had the opportunity to improve both my 100 and 200m times, but I guess now it's back to business and time to try and get some good form in the 400m for the world championships and put up a good show in the world champs in London this year."
Eight-time Olympic champion Usain Bolt has hailed van Niekerk as his successor as leader of the sprinting world, with the Jamaican legend due to retire after the world championships in London in August.
Van Niekerk is the only man in history to have run under 10 seconds for the 100m, 20sec for the 200m, and 44sec for the 400m.
He is the fastest man this year in the 200m, and will be expected to beat American Fred Kerley's world-leading 400m of 43.70sec on Thursday.
"There's no use in sitting on top of the rankings in the middle of the season and not finishing off strong, as that's where I'd like to be at the end of the season," he said.
Last week's 300m was the longest race van Niekerk has run since winning Olympic 400m gold.
"I knew it was going back to the lactic days and getting used to that feeling," he added.
"I tried to go out in the first 200 metres quite strong, and I think that when I got to the last 100 metres I felt very comfortable."
Other big names in action in Lausanne include pole vault world record holder Renaud Lavillenie, Dutch sprinter Dafne Schippers and Olympic triple jump gold medallist Christian Taylor.