Cardiff's Millennium stadium makes history when it hosts the first indoor stage of the World Rally Championship.
The stadium has been transformed for the event
On Saturday, cars will start the 1km test from the basement of the Welsh Rugby Union building and leap into view over a purpose-built jump.
They will then tackle a figure-of-eight course on the asphalt stadium floor, complete with obstacles.
For spectator safety and better viewing, the lower tier of the stadium has been removed.
Rally spokesman John Holton said it was the first time anything like this had been attempted.
"The drivers think it's an absolute delight," he told BBC Radio Wales. "Many of them are natural showmen and they will, I am sure, put on a wonderful show. You will see cars going sideways for much of the course.
"With the help of the stadium authorities, the hallowed turf has been safely removed, revealing the asphalt surface underneath.
"On that we have created - in simple terms - a figure of eight, and over that course every competitor will go against the clock, one car at a time.
WALES RALLY GB TIMETABLE
Friday 16: Six forest stages in west and south Wales, 0758 BST from Brechfa to Rheola
Saturday 17: Seven forest stages in mid and south Wales, 1028 BST from Crychan and spectator stage in the stadium
Sunday 18: Four forest stages in south Wales, 0758 BST from Resolven to Margam; finish in Cardiff
"This is a special stage of the rally, just the same as the stages running through the forests. It is a genuine, competitive part of the route and part of the official results of the event."
The UK leg of the World Rally Championship started in Swansea on Friday.
Rally officials welcomed the Welsh Assembly Government's announcement that the event would stay in Wales until 2011.
British governing body, the Motor Sports Association (MSA), said the Wales Rally GB had gone from "strength to strength".
This weekend's race started with stages through the Brechfa forest and ends in Cardiff on Sunday.
The five-year extension is estimated to be worth £40m to the Welsh economy
MSA chairman John Grant said: "There are in fact very few locations in Great Britain that can offer what Wales can.
"The rally enjoys the support of the capital city and has developed a special relationship with Cardiff City Council and in terms of the sport, the environment is superb with those fantastic forests through which most of the rally runs."
Andrew Davies, the economic development and transport minister, made the sponsorship announcement during a conference at the rally centre near Swansea on Thursday.
Several young Welsh drivers are competing in the rally - many of them as amateurs.