Behind them, just one point apart, are Spanish rival pairs Fernando Echavarri and Tara Pacheco and Iker Martinez and Olga Maslivets.

But with six races and Sunday's (September 10) medal race still to go, the 2017 Championship is wide open with just 10 points between the first seven crews.

Italian pairs won all three races today.

Now sailing with Maelle Frascari, Italy's 2016 Rio Olympic helm Vittorio Bissario won the first race.

They were the first crew to start close to the pin, at the left end of the start line, and broke away first to the favoured left.

By contrast compatriots Tita and Banti had a poor start and had to fight back to 15th in the 24 boat gold fleet.

Britain's Ben Saxton and Katie Dabson suffered a U-flag disqualification which, after a 15th in the third race, dropped them from second to fifth for the day.

They were not the only challengers to come to grief.

New Zealand's Gemma Jones and Jason Saunders went 2,8 to lead the regatta and then capsized in the third race to finish 24th.

The leaderboard roller-coaster continued as France's top duo Moana Vaireux and Manon Audinet, based in La Grande Motte for much of the year, made their second bad start from three to finish 18th, dropping to seventh.

And the Danish duo of Lin Ea Cenholt and Christian Peter Lübeck, who had finished top of the qualifying series, could only manage 16,13,13 - dropping from first to fourth.

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, the first competition to feature a newly configured foil design.

Racing continues tomorrow and Sunday, when the concluding medal race will take place.