AB de Villiers said that the inability of South Africa's bowlers to deal with Colombo's sapping heat played a major role in the 180-run loss on Saturday, after the attack conceded 320 for 5. South Africa prevented Sri Lanka from achieving a quick start after electing to field first, but were woeful at the death, conceding 137 in the last 12 overs.

Sri Lanka's total was propelled by a 134-ball 169 from Kumar Sangakkara, who built steadily alongside Upul Tharanga and Mahela Jayawardene before embarking on a manic pace in Lahiru Thirimanne's company. He hit 103 in his last 46 deliveries, and was bowled by Ryan McLaren in the 46th over, only for the delivery to be called a no-ball because too many fielders had been stationed on the fence.

"I don't think we started badly," de Villiers said. "Going at four or five runs an over was a good effort on that wicket. There's a lot of heat out there and I think the bowlers took a lot of strain. We let it get to us. I tried to keep their spells nice and short, which we managed to do. Unfortunately we lost a bit of momentum when Sanga and Jayawardene got that partnership going. There was another partnership after that and then the no-ball and the wickets - things didn't go our way there."

South Africa continued to bowl short throughout the innings, with little reward on a slow surface, but de Villiers said it was not the bowling strategy, but the attack's indiscipline that spurred their downfall. Pinpoint yorkers were scarce in the latter overs of Sri Lanka's innings, with both Sangakkara and Thisara Perera succeeding in hitting over the top in the final flourish.

"I think execution was the problem at the death, when the bowlers were tired. The fields were set and the balls kept flying, and then you add Sanga's class to that. He manipulated the fields really well. Once you brought the fine leg up, he'd play the lap shot and if we had limited men on the off side he'd manipulate there. I don't think our plans were bad."

South Africa's chase was effectively scuttled by the 17th over, as the visitors continued to lose quick wickets in pursuit of quick runs. They succumbed for 140 in the 32nd over, but were missing three top batsmen, with Jacques Kallis and Graeme Smith not with the squad and Hashim Amla sitting out the match with a neck injury.

"We lost wickets early on, which was a problem," de Villiers said. "I thought they executed their skills well. We tried too many big shots and tried going for boundaries instead of working it around and getting into the game. We didn't have a pattern of play with the bat in hand. There were no partnerships and we kept losing wickets at the wrong time."

"We definitely missed Hash [Hasim Amla] today. He's a world-class player and the number one batter in the world. We'd have liked more stability up front. Without him, our order looks a little light but there are still no excuses to be four or five down with 60 or 70 runs on the board."

De Villiers also defended his decision to bowl first, with his team then having to chase under lights. The Premadasa surface has in the past become noticeably slower in the second innings of an ODI, but de Villiers suggested that conditions remained good for batting throughout the match, despite his side's collapse.

"We looked at the past statistics and eight out of the last ten games had been won by the team chasing. Also, when I looked at the wicket this afternoon, I realised it wasn't going to change much over 100 overs. At night, with maybe a bit of dew and having cool conditions to bat in, I thought it was a very nice chance for us to chase. But 320 was a bit much and we were under pressure."

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. He tweets here