The stark contrats between South Africa's dominance in Colombo on Sunday and the manner in which they were dominated in Pallekele on Wednesday is what frustrated AB de Villiers the most as his team continue their preparations for the 2015 World Cup. For the South African captain, the swing in the margin of results - from winning the first ODI by 108 runs to losing the second by 87 runs - illustrates erratic form that does not bode well for a major tournament.

"It's never nice to win one and then lose one - you look like an inconsistent team," de Villiers said. "We should have got closer. I don't like us to lose not being in the game the last 10 or so overs."

South Africa's chase was all but over after they lost five wickets for 26 runs in the middle of their innings to tumble from 101 for 2 to 127 for 7 in little under nine overs. De Villiers accepted the bulk of the responsibility for the collapse, saying that it was his wicket which triggered it.

From there on, Tillakaratne Dilshan and Sachithra Senanayake spun a web around South Africa by exploiting the home conditions which favoured a touch of turn. De Villiers admitted it was a tough wicket to bat on "especially batting second," but said South Africa would not use the surface or the advantage to be gained from batting first as an excuse for their poor performance.

"All three games I've played here, the guys batting second have lost the game but that is not an excuse," he said. "I thought 250 was par. This was just above par but it was still chaseable. We felt if we were there in the 40th over, we'd have a chance of winning it."

After being bowled out in the 39th over, South Africa did not put themselves in a position to take that chance but that does not mean they have squandered all the opportunities they will have on this tour.

Saturday's match in Hambantota is a decider and de Villiers expects "conditions which suit us a lot more".He hoped his team would not disappoint again. "We are under pressure to win that last game," he said. "But we would love to win a series away from home and we are still in the running to do that."

For South Africa to achieve that, they may have to rethink their team composition, especially since Dale Steyn picked up an injury in Pallekele. Steyn confirmed there was no fracture to the his right thumb, but that "he couldn't bend his thumb and index finger so it was impossible for him to bowl". The seamer will receive treatment to determine his availability for the next match.

If Steyn is ruled out, South Africa may have to rethink their combinations but de Villiers said he was not in favour of drastic changes. "You can't plan for injuries in a game. It happens once in a while. I don't think there is anything wrong with our bowling options but we will obviously have a look at our team."

South Africa's options would be to include Wayne Parnell, or to opt for an extra batsman in Faf du Plessis. But that can only happen if Jacques Kallis can pick up some of the slack with the ball. At the moment, that seems unlikely.

Although South Africa have a new set of questions to answer, de Villiers remained upbeat despite his disappointment and concerns over South Africa's inconsistencies.

"The mood in the camp is fantastic," he said. "You can always judge a team's mood by the four guys that are not playing and they have done a fantastic job. I am looking forward to take things forward and trying to win the series."