* Rain forces qualifying switch to Sunday
* Session now set for 0900 local time
* Champion Hamilton fastest in final practice (Adds details, quotes)
By Alan Baldwin
AUSTIN, Texas, Oct 24 (Reuters) - Heavy rain washed out qualifying for the U.S. Formula One Grand Prix on Saturday with the session rescheduled for Sunday morning, weather permitting.
With hardy fans huddling in the grandstands, teams and drivers did their best to keep spirits up with a range of pitlane antics relayed on the television screens.
But after five half-hour delays at the Circuit of the Americas, and the rain and wind only intensifying, organisers gave up the struggle and set a new time of 0900 local (1400 GMT) on race day.
If qualifying cannot be held then, the times from final practice will set the starting grid, another boost for world champion Lewis Hamilton who was fastest in that session for Mercedes.
Hamilton will take his third world championship after Sunday's race, with three rounds remaining, if he scores nine points more than Ferrari's Sebastian Vettel and two more than Mercedes team mate Nico Rosberg.
Final practice was run earlier, when the rain was less intense, without spectators being allowed in for safety reasons. When the gates finally did open at noon, the cars remained out of sight in the garages.
"The rain is so hard that no wet tyre can take the cars round safely. Why we are all wasting our time for delays, delays, delays?," said Mercedes non-executive chairman and retired triple champion Niki Lauda before the final postponement.
Formula One has held qualifying sessions on the Sunday before now, most recently in Australia in 2013 when rain and poor light forced the delay.
The Japanese Grands Prix in 2004 and 2010 also saw Sunday qualifying due to a typhoon and rainstorms lashing the Suzuka circuit.
The rains, fuelled by the remnants of Hurricane Patricia that hit Mexico's Pacific coast on Friday, inundated many parts of Texas and triggered flash floods.
The race is scheduled for 1400 local by which time the weather is expected to have improved sufficiently.
In the absence of any track activity, mechanics and drivers put on their own entertainment.
Red Bull's Daniel Ricciardo and Daniil Kvyat performed country dancing moves, Rosberg played around with a soccer ball and a Force India mechanic showed off some breakdancing.
Toro Rosso's Dutch teenager Max Verstappen produced a fishing rod while father Jos, a former F1 racer, donned overalls and helmet and squeezed into the car while team mate Carlos Sainz's father did the same.
Sauber mechanics 'paddled' down the pitlane in a crate on wheels, with a propeller on the end, pulled by others. (Editing by Frank Pingue)