Australia are poised to capitalise on a collision between two of their greatest rivals after an eventful first day of the penultimate round of the SailGP series on Sydney Harbour.
Tom Slingsby's series-leading Australian team finished third and seventh in the first two races, but fought back to win the final one and sit joint second for the round with the United States on 16 points.
Both are five behind Spain, with only the top three of the eight boats after Saturday's two remaining fleet races qualifying for the final.
The big moment on Friday came at the start of the final race and it involved Japan and Great Britain, running third and fourth respectively heading into the round.
The British F50 catamaran skippered by quadruple Olympic gold medallist Sir Ben Ainslie ploughed into the Japan boat, slicing off its bow, with neither boat able to continue.
Japan driver Nathan Outteridge said the only way his boat could race on Saturday would be if they could get some equipment from the British team.
Representatives of both boats seemed open to the idea, but weren't sure whether that was allowed under the rules and were checking with series officials late on Friday.
"If Ben wants to offer equipment to us we'll gladly take it, but I don't think he's obligated to do so," Australian Outteridge told AAP.
He said no one on his boat had been hurt and tempered his criticism of the GB boat after initially describing its action as reckless.
"It wasn't malicious. There's six people on board and you've got to try and look around and use everyone on board to spot the boats," Outteridge said.
Ainslie accepted the British boat had made a mistake.
"The Americans, we were in a defensive mode against them and I just completely didn't see the Japanese team at all," Ainslie said.
"I think right at the last moment someone said see the Japanese and by that stage we just came into them sideways which was obviously devastating for both teams."
The likely imposition of penalty points could scupper the GB team's prospects of finishing in the top three and racing in the $US1 million grand final off San Francisco early next year.
"I think sadly it probably means the end of our season in terms of having a chance of winning the season and being in the final in San Francisco because we will most probably pick up some (penalty) points for the damage," Ainslie said.
Slingsby acknowledged any penalty points against GB would help his team, while admitting his team had an up and down day.
"We didn't sail that great today. We got lucky in that last race and we come away with a good result and it saved the day for us," Slingsby told AAP.
Spain won Friday's first race from GB and Japan controlled the second, winning from Spain.
The USA, who are running second in the overall standings, improved through the day, scoring a sixth, third and second.
"I had a tough day I struggled to get off the start line in all of those races," said US team driver Jimmy Spithill of Australia.
Outside the top three after Friday were Denmark 14, Great Britain 12, Japan 10 New Zealand nine and France seven.
