South Africa are determined to put the pressure back on England after blowing away the cobwebs in their opening Royal London Series defeat at Headingley.
Faf du Plessis admits the tourists - number one in the world one-day international rankings - were well short of their best and made "silly mistakes" to go 1-0 down with two to play.
But after arriving on the south coast for Saturday's match at the Ageas Bowl, South Africa's number-three batsman expects a significant improvement.
"We were disappointed with the way we played at Leeds - that's probably the most mistakes we've made in a game for a while," said Du Plessis.
"But England put you under a lot of pressure, and you have got to make sure you are on top of your game and transfer the pressure back on to them."
Du Plessis and opener Hashim Amla put South Africa in position to chase England's 339 for six. But both then got out, and from 145 for one AB de Villiers' team faltered to 267 all out in 45 overs.
"We've played some really good cricket over the last while, so that last game was a bit of cobwebs," added Du Plessis.
"We made some silly mistakes tactically, so hope we can do better this time."
South Africa are most concerned with rising to the challenge at next month's Champions Trophy, but it will be poor preparation if they do not push England hard in the remainder of this series.
Du Plessis said: "It's about making sure you are gearing up to play your best cricket when the tournament is at its peak.
"At Leeds we got ourselves in a position where we could have possibly won the game with the bat... and with our strong middle order we should have done better.
"From a bowling point of view we made a lot of silly mistakes and gave the English batsmen too many free runs."
South Africa have the option of giving a losing line-up a second chance or perhaps bringing specialist seamer Morne Morkel in for one of their bowling all-rounders.
