Perth,  South Africa's Mignon du Preez believes her side has finally "shaken the monkey off their back" after steering her side to their first Women's T20 World Cup match victory over England.

du Preez, who has featured in all seven editions of the tournament, on Sunday celebrated her 100th T20I appearance in style by hitting back-to-back boundaries in a thrilling final over against her country's former semi-final nemesis.

England, who set a chase of 124 thanks to Nat Sciver's half-century, looked like they were en route to an expected victory at the WACA but an impressive late showing from Chloe Tryon and two big hits from Mignon turned the game on its head in the final over.

They may have left it late but du Preez was delighted to lift the Proteas over the line and said her side's ability to hold their nerve will hold them in good stead for the rest of the tournament.

"It's nice to finally beat them in an ICC tournament," said du Preez. "This is the seventh one I've played in and we've never got close before.

"To put that behind us and move forward is really exciting. We've always known how strong we are and that within the team we have match-winners but we had a monkey on our back.

"I've played enough games in my career to be able to step up in crucial moments and I think to finally do that and contribute to the team is really special.

"This will give us the boost we need to go one step further than the semi-finals and take a World Cup trophy home. We know we're good enough, we just have to play well and enjoy it.

"It's the biggest Women's T20 World Cup so far and it's such an honour to be a part of it."

It wasn't just with the bat that South Africa impressed as a three-wicket haul from Ayabonga Khaka and two apiece for van Niekerk and Kapp stopped England's middle-order batters in their tracks.

South Africa will now face Thailand in their second Group B game on Friday.