The home team won the first Test by an innings and then went down to a 208-run defeat in the second match.
Cape Town: South Africa must be mentally stronger in the third and final Test against Sri Lanka, captain Graeme Smith said on the eve of the match.
The home team won the first Test at Centurion by an innings and then went down to a 208-run defeat in the second match in Durban last week.
"I can't fault the training nor the effort, the players have been outstanding. But mentally we need to be a bit stronger, that's the only thing I can put my finger on," Smith told reporters on Monday. "We just didn't adapt well to conditions in Durban and recently we haven't played our best cricket in those conditions."
"It's easier for us when the ball goes through and there's good carry but when it doesn't we need to adapt, we need to shift mentally," added Smith.
Sri Lanka had failed to win their eight previous Tests in South Africa before Durban. "We have had a very hard time here and before the series everyone was saying we are underdogs and can't beat South Africa," said visiting skipper Tillakaratne Dilshan. "But if we play our brand of cricket and stick to the basics we believe we can perform in any conditions."
South Africa have made two changes to their team, Alviro Petersen replacing batsman Ashwell Prince and seam bowler Vernon Philander coming in for the unlucky Marchant de Lange. Petersen will open with Smith while Jacques Rudolph drops down to number six. Philander, who has taken 24 wickets in his first three Tests, returns after a knee injury kept him out in Durban. Debutant De Lange picked up seven wickets in the first innings of the second Test.
Sri Lanka are sweating on the fitness of wicketkeeper-batsman Dinesh Chandimal, who arrived in Test cricket with a bang by hitting two half-centuries in Durban. He is a doubt after he was struck on the elbow while batting in the nets on Sunday.
"Chandimal's elbow is getting better but it's a bruise in a nasty place. It would be a loss for us if he can't play because he did a great job for us in the last Test," Dilshan said.
Dilhara Fernando is also doubtful with a knee problem and seamer Dhammika Prasad is standing by to replace him.
The pressure is on South Africa to put another infuriatingly inconsistent year behind them.
"All these ups and downs, it's been the story of my career," said Smith. "I've played under that pressure since I was 22 and I was probably stupid to take the captaincy at that age. But it's about bouncing back and getting things right over the next five days."