"The unpredictable nature can count against them, but it can also be a major bonus for them. The key for us is to adapt to the conditions better than the other team," Smith said ahead of Thursday's match.
The West Indies beat South Africa in the 2003 World Cup and in the Champions Trophy in England the following year. The defeats contributed to South Africa's failure to enter the semi-finals on both occasions.
But Smith denied it was a grudge match.
"I am sure it is going to be very competitive. The teams have had a mixed relationship on and off the field. Certain guys get on well with each other, but otherwise we don't know each other too well," he said on Wednesday.
Defending champions West Indies began their group matches on a sensational note when they defeated world champions Australia. They also beat India before losing to England in a 'dead' match.
The South African captain said his team needed to stick to their plans and keep pressure on the West Indies, who had more than one match-winner in their ranks.
"The West Indies have match-winners and, in one-dayers, one match-winner can win you a game. They have got the likes of Chris Gayle, Ramnaresh Sarwan, Brian Lara and Jerome Taylor," said Smith.
"If you can really get them under pressure and get stuck into their middle order as quickly as possible, then we will go a long way in curbing their strengths."
Smith did not believe their top-order batting was a major cause of concern, saying he was confident the batsmen would come good in the crunch match.
South Africa had played three matches on different pitches, scoring 108 against New Zealand, 219 against Sri Lanka and 213 against Pakistan.
"It is just a matter of spending some time in the middle. You have got to make a good start and take it from there. We have got guys to perform well," said Smith.
"I think most top-order batsmen have so far struggled in this tournament. I think the new ball has been a difficult phase to bat. If we can get off to a good start, it will be a huge bonus for us."
Mark Boucher, Justin Kemp and AB de Villiers are the only batsmen to have scored a half-century, while Smith, Jacques Kallis and Herschelle Gibbs are yet to fire.
"It's time all of us delivered. The pressure is there on everybody in a semi-final. Whichever top order gets off to a good start, it will allow the rest of the guys to play a far more attacking and aggressive game."
Smith said his batsmen needed to adapt themselves to the pitch here because it looked a bit inconsistent.
"This wicket looks different from the ones we have played on. It seems a bit two-paced and inconsistent. Every pitch has been different and adapting to the conditions has been the key," said Smith.
West Indies captain Brian Lara was confident his team would put in an impressive performance against second-ranked South Africa, saying they had been playing good cricket in recent months.
"South Africa may be favourites assessing the present situation, but we now know our game better. The challenge is there, but we are playing good cricket at the moment," said Lara.
The West Indies beat India 4-1 at home in May, qualified for a triangular one-day series final in Kuala Lumpur in September and then won four of their six matches in the ongoing tournament.
"The boys have started believing in themselves. Things have worked out well for us in this tournament. We have set and chased totals and we are well prepared," said Lara.
"We are quite happy with the way the guys are expressing themselves and we know exactly what we want to do against South Africa."
South Africa: Graeme Smith (capt), Jacques Kallis, Loots Bosman, Mark Boucher (wicketkeeper), AB de Villiers, Boeta Dippenaar, Herschelle Gibbs, Andrew Hall, Justin Kemp, Charl Langeveldt, Andre Nel, Makhaya Ntini, Robin Peterson and Shaun Pollock
West Indies: Brian Lara (capt), Ramnaresh Sarwan, Carlton Baugh (wicketkeeper), Ian Bradshaw, Dwayne Bravo, Shivnarine Chanderpaul, Corey Collymore, Fidel Edwards, Chris Gayle, Wavell Hinds, Runako Morton, Marlon Samuels, Dwayne Smith and Jerome Taylor