The Australia SailGP Team's bid for Championship glory took an unfortunte turn on Thursday as the Flying Roo capsized in San Francisco Bay during a practice session for the Mubadala United States Sail Grand Prix.

The Aussies, who lead the Championship and have already booked their place in the three-team winner-takes-all Grand Final, took their F50 out as the fog descended on San Fran and unfortunately keeled over - with damaging consequences.

Whilst no injuries were sustained by any of Tom Slingsby's crew, the F50 wing showed visible damage when the boat was righted, with further assessments planned when the team return to the Tech Base.

Slingsby and co can take it easy over the five Fleet Races in San Fran, having guaranted their place in Sunday's Grand Final race.

They will be joined in the winner-takes-all shootout by the home United States team, with the third finalist still undecided.

Both Japan and Spain can still qualify for the Grand Final race, with the pressure on heading into Race Day 1 on Saturday.