The duo are ranked a lowly 33rd in the world rankings but delivered a series of consistently strong performances.

They finished second in race one before first placed finishes in the next two for a leading haul of just four points.

But then disaster struck as a successful post race protest saw them penalised for sailing with the rubber bushes at the top of the foils removed.

This is contrary to the International Jury’s interpretation of the measurement rules.

They were given a 50 per cent penalty in each of their races to slide to 40 points for 27th place.

This meant British teams occupied first and second positions in the mixed event category.

John Gimson and Anna Burnet sit firstd, on nine points, after a second, third and fourth place finish today.

Ben Saxton and Katie Dabson lie second on 12th place after crossing sixth, fourth and second.

Gemma Jones and Jason Saunders of New Zealand rose to third, a further point behind.

Reigning Olympic champions and competition favourites Santiago Lange and Cecila Carranza of Argentina lie ninth, on 19 points, after a disappointing first day of competition.

There remains a long way to go, however, with 19 individual races scheduled before the medals are allocated on Sunday (September 10).

It came after another American Bora Gulari lost part of three fingers on his right hand in a training accident late last week before competition began..

Gulari, seventh at Rio 2016, had been training alongside team-mate Helena Scott when he came in contact with the boat's rigging during a capsize in strong wind conditions.

He was forced to withdraw but hopes to return to the water within the next four weeks.

The mixed Nacra 17 class first featured on the Olympic programme at Rio 2016 and is due to return at Tokyo 2020.

The World Championships are, however, be the first competition to feature a newly configured foil design.

Action is scheduled to continue tomorrow.