British team officials have yet to name Team GB's 49er crew for the Games, with a number of partnerships vying for the one available slot in the skiff fleet.
Despite being together just two years, Evans and Powys were the top-ranked British boat at last year's ISAF World Championships and moved into the fleet lead at the ISAF World Cup in Palma.
But domestic rivals John Pink and Rick Peacock are not far behind in fifth.
“It feels like we’ve been thereabouts for a while,” said Powys.
“We feel we’ve made some massive improvements over this winter and are very much on an upward trajectory with more to give.
"It’s just about keeping that momentum going and cutting out some of the avoidable mistakes which is what we hope to do this week."
Elsewhere, three-time Olympic champion Ben Ainslie moved into the lead in the Finn fleet after picking up a first and second and there was better news for Iain Percy and Andrew Simpson, in their first competitive outing since Percy's back injury halted their world title defence in Perth last year.
The Olympic champions in the Star fleet made amends for a forgettable first day to record a first and seventh, moving to third overall.
“Andrew made the point before the event that we’ve basically completed four races in eight months, so we’re really rusty on the racing side, which is fine and we always knew that was the case," said Percy.
"But over the next few months we’ve got quite a lot of competitions – the World Championships, here, Hyeres, going into Skandia Sail for Gold and the thing for us is to use those regattas to get race sharp before the Olympics.”