Defending champion Ryf began as the favourite to claim the women’s crown at Nelson Mandela Bay in Port Elizabeth.

The Swiss triathlete claimed gold at the European Championships last month and produced an impressive display to clinch a fourth world title.

She finished the 1.9 kilometre swim in a time of 26min 45sec, before moving into the lead over the 90km bike leg.

Ryf would head into the run with the lead and she maintained her advantage throughout the 21.1km course to clinch victory in a time of 4 hours, 1min, 12sec.

The Swiss athlete has won the half-distance Ironman event four times in the past five years, with her only absence from the top step coming in 2016 when Britain’s Holly Lawrence won the title.

Britain’s Lucy Charles finished as the runner-up in South Africa, as she ended 3:46 behind the winner.

The podium was completed by Germany’s Anne Haug, who achieved a time of 4:07:21, over six minutes down on Ryf’s time.

The men’s race will take place tomorrow.