Both sailors achieved a victory and a second-place each and have three points at Sandringham.

World number 36 Alexander is a surprise co-leader as his team-mates Matt Wearn and Tom Burton were considered those most likely to impress for the hosts.

"I got two good starts at the boat end and then it was about playing the long shifts throughout the day," he said.

"They were long tacks, so you just had to be patient."

Stipanovic won Olympic silver at Rio 2016 and described conditions as "really great".

Philipp Buhl of Germany was first and fourth and has five points in third overall.

Reigning Olympic and world champion Burton is 29th on 20 points.

He has a point to prove after Australia overlooked him for the Tokyo 2020 Olympics in favour of Wearn, the world number one.

Wearn ended the day 10th on ten points.

Forty-seven-year-old Brazilian Robert Scheidt, the 1996 and 2004 Olympic champion, finished day one with 27 points in 40th place.

Competition continues in Melbourne tomorrow.

The event is a key event in the build-up to Tokyo 2020, with sailors battling for national selection.