Samoa are bracing themselves for a South African backlash when the teams square up at Villa Park at the weekend.
The Springboks, two-time World Cup winners, are still licking their wounds following the humiliating defeat to minnows Japan at Brighton on Saturday.
Samoa were hardly convincing in their opening match but at least avoided a similar fate as they saw off the United States 25-16 on the same ground a day later.
Japan's remarkable win has blown Pool B wide open and Samoa coach Stephen Betham admits rugby's traditional superpowers have had to sit up and take notice.
“Japan’s victory doesn’t change anything, other than if anything it’s woken everybody up,” he said.
“It’s the World Cup; everyone brings their best team, and the teams who take their chances can beat anyone.
“The tier one nations have had a wake-up call. There will be a backlash from South Africa but we’ll be prepared for it. Our surprise factor has gone, so they will come out all guns blazing.”
Tries from Tim Nanai-Williams and Ofisa Treviranus, plus 12 points from the boot of Tusi Pisi, secured Samoa's victory, with Chris Wyles and Chris Baumann replying for the USA.
Eagles captain Wyles said: "At times we physically matched them, but our discipline let us down.
“But we were still in a position to win, which is a huge positive despite some of our loose play.”
Next up for the Americans is a Sunday encounter with Scotland — who first have the small matter of a meeting with rugby’s new darlings on Wednesday.
US coach Mike Tolkin does not expect Japan to take their eye off the ball despite their heroics against the Springboks.
He said: "One of their hallmarks is that they are very disciplined, so (coach) Eddie Jones will have them focused and ready to go, forgetting about the win — if that's possible.
“It was a fantastic, historic win for Japan, and for our circle. We play them quite a bit and they are always close games so for teams like that to be on the rise is great for the game.
“We have extra rest, which always helps after an international.
“What will we do differently against Scotland? Win, hopefully.”
