The attendance for this weekend's US Grand Prix in Indianapolis is expected to fall well short of that seen in previous years.

More than half the spaces for Sunday's race will remain unfilled, with organisers expecting a crowd of between 120,000 and 140,000 fans, according to the BBC World Service.

Perversely, that will still be the largest crowd for a Formula One race this season - but is significantly down on the 2001 figure of 175,000.

And it could be little more than 50% of the 2000 attendance figure, which was estimated at around 200,000.

Falling trend

Race officials are pinning the blame for the slump on the US recession and the domination of Ferrari driver Michael Schumacher, who clinched the world championship in July.

It will not be the first time this season that attendances have fallen.

At last week's Italian Grand Prix, track officials reported a race-day crowd of 60,000, down from 72,000 last year and 80,000 in 2000.

And at the Hungarian Grand Prix on 18 August, where Ferrari clinched the constructors' championship, there were significant gaps in the normally crowded grandstands.

And TV figures have also fallen across the globe.