Johnston celebrates dismissing South Africa's Herschelle Gibbs

Ireland had South Africa in trouble at 91-8 but the world's top one-day side recovered to set a total of 192.

"My major goal for my team at this World Cup is to be competitive and we have shown that we are in this first match," said Johnston.

"Our bowlers did very well. We made good use of the new-ball pitch."

Interview: Ireland captain Trent Johnston

He added: "This was really great after the struggles we had in Kenya recently.

"We have had a good start and hopefully we will be able to put other areas of our game together so we will be hitting the straps when we meet Zimbabwe in our opening game."

South Africa's coach Mickey Arthur blamed lack of match practice for his side's indifferent batting.

"The guys haven't had a hit for about two weeks and hence the performance you saw out there," he said.

"They will come good at the right time. We don't want to peak too early. The batting will come good soon."