John Smith and James Thompson at the Lightweight Men's Double Sculls Final race at the Rowing World Cup on Lake Rotsee in Lucerne, Switzerland. Photo: Urs Flueeler

Cape Town - John Smith and James Thompson won rowing gold for South Africa at London 2012, before the breakup of their lightweight fours team forced them into a rapid reinvention.

The duo paired up to take on the lightweight double sculls and in a short space of time have emerged again as genuine medal contenders.

Four years ago, Smith and Thompson teamed up with Matthew Brittain and Sizwe Ndlovu to dash the home hopes of Britain's fancied team and win South Africa's only rowing gold.

A recurring back injury, however, forced Brittain to retire and pushed Smith and Thompson in a new direction.

“I always thought it would be extremely difficult to switch, but they have made it look easy,” said Brittain.

“Of course it's easier to become good at one if you have already mastered the other, but it's very unusual to be exceptionally good at both.

“But the double seems to suit them because it's more about power than the four and they are both really strong.”

The South Africans have high hopes in what is expected to be an open race with no one team claiming ownership of the lightweight double sculls in the lead-up to the Games.

A different crew has won the world championship every year, since the Danish pair of Rasmus Quist Hansen and Mads Rasmussen won Olympic gold in 2012.

The most consistent pair have been Norwegians Kristoffer Brun and Are Strandli, but Smith and Thompson have set the world-leading time heading into Rio.

“Obviously James and John have the experience to know how to approach the event, but the Olympics is so big that it can throw even the toughest competitors. They will be against some serious competition,” said Brittain.

“If nothing unforeseen happens, I think the final will be close. It will probably come down to whoever trained better during the six weeks since the last time they raced each other.”

The lightweight double sculls heats on Rodrigo de Freitas Lagoon begin on Sunday with the final next Friday.