Frodeno, who grew up in South Africa, dominated a massively strong field in Nelson Mandela Bay, holding off the challenge of Britain’s double Olympic champion Alistair Brownlee and Spain’s five-time world champion and defending champion Javier Gomez.

The 37-year-old Beijing 2008 Olympic champion set the pace at the front of the 1.2-mile swim, which he completed in 21min and 52sec and then worked with Brownlee to stay at the head of the 56-mile bike ride, which took 2hr 28min 04sec.

Brownlee pushed ahead of him early in the concluding run, but then Frodeno took off, running the half marathon distance of 13.1 miles in 1hr 06min 33 sec to secure the victory in 3:36:30 in a race which was effectively a half-Ironman.

Gomez, who also came flying out of transition, ran up to leader Frodeno's shoulder and settled into second position.

By the 10km mark, Frodeno and Gomez had opened up a 30-second gap over Brownlee.

Frodeno made his move with just a few miles to go, and shortly after, Gomez began to slow, grabbing at a side stitch, with Brownlee soon moving past him.

Frodeno was alone for the rest of the run, with Brownlee finishing just over a minute behind him in 3:37:41, while Gomez held on for third in 3:38:26.

"I'm very happy, what a special day," said Frodeno.

"To come here is special, and to perform in front of a home crowd is just epic.

“To be world champion is surreal.

“I was a little angry because Alistair and I did all the work on the bike and nobody else tried to do anything.

“But somehow today I just had my running legs.

“I didn’t start celebrating until the last turn - I was just running for my life and breathing so hard I didn’t hear anything else."

Brownlee commented after his first 70.3 run: “Obviously I want to win, but I gave everything so I am happy with that.

“To be honest I’ve had a tough year with injuries and a few things, I’ve just not quite been myself.

“Basically the last three or four weeks is the only training I’ve done so I’m pleased with that.”