With five overs to go in their opening match at the World T20, South Africa were 115 for 3, needing another 51 runs to win. At the same stage of their innings, Sri Lanka had been 117 for 4. That South Africa failed to get over the line owed something to Sri Lanka's wicket-taking ability and something to a familiar failing of nerve by the chasing side.

Sachithra Senanayake had delivered a tight spell and he capped it by having the set batsman, JP Duminy, caught on the boundary in the 16th over. The lurking threat of Lasith Malinga, who still had two overs to bowl, was perhaps the reason that Albie Morkel tried - and failed - to hit a third consecutive six over long-on against Ajantha Mendis in the 17th. Although the required rate continued to hover around ten an over, South Africa were now five down and the incoming batsman would find he had been left with too much to do.

AB de Villiers, captaining the side in place of the injured Faf du Plessis, said that the plan had been to make sure that no more than eight runs were required off the final over, knowing that Malinga would bowl it. They were left needing 15 and Imran Tahir's six off the last ball perhaps made the result seem closer than it had been.

"There were two areas where we lost the game," de Villiers said. "They certainly got 15 too many, we were very poor in the field. They ran twos on way too many occasions. Too many extras and we've been guilty of that in the past, so something we have to work on and have to get right if we're going to do well in this tournament.

"Then we lost wickets at bad times, I got out at a bad time. When it gets close like that and it's a crunch game, you lose wickets at the wrong time and you lose the game. We lost our momentum towards the end, we needed to get it down to no more than eight off Malinga's last over because he's a really good death bowler, we couldn't do that. Unfortunately we were just not good enough on the day, I thought we were nowhere near 100 percent and that's the disappointing part. I don't mind losing games if we play at 100 percent but we just weren't good enough today."

South Africa have been reluctant to move de Villiers up the order, despite calls for him to be given more time to affect the course of matches, but the dismissal of Quinton de Kock, a left-hander, meant JP Duminy was preferred. De Villiers reiterated the view that his skills were more required in the middle overs.

"With Sri Lanka's spinners, we felt it was important to keep that right-left combination at the crease, so when Quinton de Kock got out we thought it was the best option for us to send JP in, to keep them guessing," de Villiers said. "That's why if Hash got out, I would have gone in, just to keep them on their toes. But we feel it's important with the good spinners."

As it transpired, Amla struggled for fluency and after eight overs South Africa were 47 for 1, with the pressure beginning to rise. Duminy tucked into Thisara Perera and Mendis to help add 28 more by the halfway stage and, with de Villiers alongside him, South Africa appeared to be edging back into the contest, only for both to fall trying to force the pace. De Villiers said going after Mendis had been premeditated but his dismissal of Albie effectively ended the chase.

"It was touch and go. It could have been a six but that's the game, that's the nature of Twenty20 cricket again," de Villiers said. "One inch further and it's a six, that's how it goes. He didn't hit it in the middle - I think it comes down to execution. I think he knows he probably could have hit it better. That's how it goes sometimes, you can't blame one player. I thought we batted quite well for most of the night and unfortunately got out with that fifty-fifty chance going to hand and not over the boundary."

Losing to Sri Lanka, ranked the No. 1 side in the format, need not be terminal for South Africa's semi-final chances and they can take some encouragement from a narrow defeat. Dale Steyn recovered from his first over being hit for 17 to bowl with familiar precision and hostility on his return from injury, while de Kock and Duminy hinted at what the batting may be able to produce. Sri Lanka had raced out of the blocks thanks to Kusal Perera's sparkling innings but de Villiers said Imran Tahir "turned the game around for us" with his 3 for 26.

De Villiers was also hopeful that Faf du Plessis would return to take charge of South Africa's second game, against New Zealand on Monday.

Alan Gardner is an assistant editor at ESPNcricinfo. He tweets here