Mahe won't spill secrets to Martin

Double Olympic champion rower Mahe Drysdale.

New Zealand's double Olympian Mahe Drysdale has rolled out the welcome wagon for Croatian Damir Martin, but that stops on the edge of the Whanganui River.

The two rivals will 're-race' their epic single sculls final on the Rodrigo de Freitas lagoon in Rio for the latest edition of the Billy Webb Challenge on Sunday, amongst a strong international field that includes Germany's Under 23 world champion Tim Ole Naske, former Serbian Olympian Radoje Djeric and current New Zealand representatives Lucy Spoors, John Storey, and Brooke Donoghue.

Drysdale and Martin have been thick as thieves over the last week promoting the event, which Drysdale promises will be more spectator friendly with the new course that loops north from the township and comes back to the start/finish line at Settler's Wharf following a 5km haul

They were together on the Crowd Goes Wild television show on Monday, and will be taking some lucky punters on a leisurely waka paddle along the river tomorrow, courtesy of Whanganui waka operator Ki Tai.

"I'm looking forward to coming down and showing Damir the river," Drysdale said.

"It's been great training together, to be honest we're in similar shape - not the best.

"The young guys will certainly push us along."

This was proven on Monday when the CGW television crew surprised the Olympians as they sat down on two Erg indoor machines for a fun challenge - informing them at the last minute it was a 500m virtual race and not the agreed upon 200m.

"They sprung that on us and...it hurt more than what we would usually do," Drysdale laughed.

Wanganui Rowing Association spokeswoman Kate Austin said this was especially tough on Martin who had done a big training session that morning.

So it's all been fun and games but when Drysdale was asked if he had taught Martin some of the finer points of the Whanganui River, and how she can be a cruel mistress with subtle variations in current through to added hazards in rough weather, the competitive veteran revealed he is not surrendering that advantage.

"I thought I'd just keep that as a surprise for him, that's part of the great part of this event.

"It's an outdoor sport so you've got to be ready for anything."

Drysdale has won every Billy Webb Challenge except 2014 when a rogue floating log allowed fellow Olympic gold medallist Hamish Bond to claim line honours, so he knows what to expect on the long journey.

But far from treating this as a two-horse race, Drysdale acknowledges the likes of Storey and Naske could yet have their say in the proceedings.

Storey was back quickly from Rio where he raced in the Kiwi men's quad, and has got himself straight back into training for NZ elite squad's coming season.

He also owns a victory over Drysdale from back in January at the Cambridge Town Cup.

"John's in very good shape, been training longer than us," said Drysdale.

"The German [Naske], he's going to be tough competitor.

"The week after the Olympics, I'd back myself to beat them all, but the field has evened up."

The festivities start on Sunday with the Waka welcome and Karakia at 9.55am.

Twenty minutes later is the Air Chatham Sprint Challenge race, followed by the Display Associates Corporate 8s challenge at 10.45am.

The single sculls boats will launch at 11am with racing getting underway 30 minutes later.

Prizegiving will be at 12.30pm.