NSWIS sailor Tom Burton has made a significant move on the penultimate day of competition in the Laser class.

After starting the day ranked fifth overall, Burton held his position by finishing seventh in the opening race of the day.

Then came what could be a defining moment in his Olympic campaign, leading the fleet through the first lap of race eight and holding on to finish second.

Crucially, he made up ground on Croatian Tonci Stipanovic and Brazilian Robert Scheidt who sit in front of him on the leaderboard.

Hometown legend Scheidt is aiming for his sixth medal from as many Olympics, a feat that would consolidate his standing as Brazil’s greatest ever Olympic athlete.

It came on another tricky day at Guanabara Bay for the sailors with competition forced to be put on hold through the morning.

Defending Olympic champions Nathan Outteridge and Iain Jensen began their campaign in the 49er class and sit 11th overall after two races.

The 49er class has been billed as the re-match between the Australians and the team they relegated to silver in London four years ago, New Zealanders Peter Burling and Blair Tuke.

Day one certainly belonged to the Kiwis with the four-time world champions recording commanding back-to-back wins.

Outteridge and Jensen finished 13th and eighth to sit 19 points off the pace in 11th.

Due to time delays because of the weather conditions, race three was postponed until tomorrow.

NSWIS sailors Lisa Darmanin and Jason Waterhouse will also be back in action in the Mixed Nacra 17 class.

The Sydney-siders currently lead the competition at the halfway stage.