Wet or dry, there is no great mystery about how South Africa will play this game. If it's fluid, incisive, spin-it-wide rugby you're looking for, forget it.
There's a clue on the South African bench - a five-two forward-back split, with three frontrowers - so a degree in rugby tactics is not required to know what's in store for Wales.
"They're big guys, eh," quipped Wales' captain, Sam Warburton, yesterday. He'd seen some of the opposition in the street the other day.
Not that Wales are short on beef themselves, but their record of one win and a draw from 25 clashes doesn't bode well.
Last year Wales lost 34-31 and 29-25 to the Springboks. They feel the gap is closing, even so.
"We're not going into this game hoping they have a bad day and everything goes well for us," he said.
"We are going in with some confidence. We've had a good warmup preparation, we feel physically in great shape and looking forward to Sunday."
Gatland has put his faith in young Rhys Priestland, with just four caps to his credit at first five-eighths, placing talented and versatile James Hook at fullback.
First choice pivot Stephen Jones is battling a calf injury, as are prop Gethin Jenkins and loose forward Ryan Jones, so Gatland's selection options were limited.
No Springbok will look down on lock Luke Charteris at 2.06m and the loose forward contest will be intriguing.
Warburton, who turned 23 five days ago and has just 17 caps to his name, has created a strong impression, and his battle with bustling Springbok fetcher Heinrich Brussow could be one of the key tussles.
"A lot of people haven't seen Sam Warburton, but I think he'll create an impact after a few games in this World Cup," said Gatland.
Warburton has another capable pair with him in the back row in Dan Lydiate and newcomer Toby Faletau.
Mike Phillips is a robust, resourceful halfback, Jamie Roberts is a blockbusting second five-eighths, and wings George North and Shane Williams - one strapping, strong-running and 19, the other diminutive, quick-footed and 34 - will fancy making a dent given the chance.
As for the Springboks, Danie Rossouw gets Bakkies Botha's spot at lock alongside Victor Matfield and there are no real surprises elsewhere in the side named yesterday.
Discipline will be a key for Wales. Morne Steyn will damage them if they're infringing within 40m of their posts.
The cup needs an early upset, an event to make the rugby world sit up. Might tomorrow be Wales' hour?
Wales v Sth Africa
Wellington, 8.30pm, Saturday 10 September
Referee: Wayne Barnes (England)
Wales
James Hook
George North
Jonathan Davies
Jamie Roberts
Shane Williams
Rhys Priestland
Mike Phillips
Toby Faletau
Sam Warburton (c)
Dan Lydiate
Luke Charteris
Alun Wyn Jones
Adam Jones
Huw Bennett
Paul James
Reserves: Lloyd Burns, Ryan Bevington, Bradley Davies, Andy Powell, Tavis Knoyle, Scott Williams, Leigh Halfpenny.
South Africa
Frans Steyn
JP Pietersen
Jaque Fourie
Jean de Villiers
Bryan Habana
Morne Steyn
Fourie du Preez
Pierre Spies
Schalk Burger
Heinrich Brussow
Victor Matfield
Danie Rossouw
Jannie du Plessis
John Smit (c)
Tendai Mtawarira
Reserves: Bismarck du Plessis, Gurthro Steenkamp, CJ van der Linde, Johann Muller, Willem Alberts, Francois Hougaard, Butch James.
