World Cup Group B, Kolkata:
South Africa 272-7 (50 overs) bt Ireland 141 all out (33.2 overs) by 131 runs
Match highlights: On the Red Button and the BBC Sport website at 2200 GMT and on BBC Two at 2320 GMT
South Africa end Ireland's World Cup
South Africa booked their place in the World Cup quarter-finals and ended Ireland's hopes of progressing with a 131-run win at Eden Gardens.
The result leaves India, West Indies, Bangladesh and England fighting for the other top-four berths in Group B.
Ireland did well to limit South Africa to 272-7 after asking them to bat, with JP Duminy out in the last over for 99.
But Morne Morkel (3-33) and Robin Peterson (3-32) impressed as South Africa bowled Ireland out for 141.
It was a brave effort from Will Porterfield's men in Kolkata, but the South African bowling attack was simply too strong and the Irish never looked like getting close to their target.
Graeme Smith's side become the first team to qualify for the last eight from Group B and they could now have a bearing on whether England join them in the knockout stage.
England can boost their hopes by beating West Indies
in Chennai on Thursday, but if South Africa lose against Bangladesh in Mirpur on Saturday it will all come down to India v West Indies a day later, with run rate a potential decisive factor.
The Proteas will not have to worry about such minutiae as they swept aside an Irish batting line-up that,
13 days earlier, had brilliantly chased down a target of 328 to beat England in Bangalore.
Ireland struggled throughout, kept in check by Dale Steyn and Morkel at the top of the innings and then strangled by Jacques Kallis and spinners Johan Botha and Peterson.
Eight batsmen managed to get into double figures but no-one managed a half-century and partnerships were in painfully short supply as South Africa successfully chipped away at their order.
They struck twice early on as Morkel proved too good for openers Porterfield and Paul Stirling and though Niall O'Brien temporarily lifted the pressure by lofting Morkel over long-off for six, soon after he feathered Kallis behind for 10.
In the process, all-rounder Kallis became only the second man to score 1,000 runs and take 20 wickets in World Cup matches after Sri Lanka legend Sanath Jayasuriya.
Dockrell (left) once more bowled with class and composure
After Ed Joyce was trapped lbw by Botha for 12, Gary Wilson and Kevin O'Brien at least managed to put together a stand of some note as they added 41, but when they fell after a few lusty blows in the same over to Peterson the game was as good as over.
Peterson's success continued when Alex Cusack sliced him to Smith in the covers, Trent Johnston was caught behind off Duminy, Mooney nicked Kallis behind and Morkel deservedly wrapped it up when George Dockrell was caught by Morne van Wyk.
Ireland's disappointing batting display was in stark contrast to their livewire performance in the field, in particular their ground fielding contributing to a lower South African total than Smith would have expected.
Hamish Amla was the first to fall, slicing Boyd Rankin to Dockrell at third man where the 18-year-old took a fine, diving catch, before Kevin O'Brien dropped Van Wyk, promoted up the order to three, at short cover.
Van Wyk was playing with freedom and crashed two fours apiece off Rankin and Johnston before he was put down again, this time by Stirling at slip.
At the other end Smith's poor recent run showed no sign of ending and he was run out by John Mooney for a scratchy seven from 18 balls. With only 101 runs in his five World Cup innings, Smith badly needs some real time in the middle.
Van Wyk's breezy knock was ended on 42 by the hugely impressive Dockrell, the left-arm spinner taking 1-37 from his 10 overs and knocking over Van Wyk's off stump as a straight one kept deceptively low.
South Africa needed partnerships to steady the innings and after Kallis was run out for 19 and Francois du Plessis edged Stirling to slip for 11, it was Duminy and Colin Ingram, making his World Cup debut in place of the rested AB de Villiers, who provided stability.
Kallis in a flap as crow halts play
Ingram broke the shackles after 81 balls without a boundary as he feasted on some shorter pitched bowling to pull and hook a spate of fours and Duminy brought up a circumspect fifty from 67 balls with a glorious drive through the covers off Johnston.
Ingram was denied a half-century of his own when Johnston bowled him for 46 and in tandem with Botha, Duminy increased the tempo towards the end of the innings, crashing two fours and six off the 49th over from Johnston to close in on 100.
He fell agonisingly short as he tried to bring up his milestone with a maximum and was well caught in the deep by Kevin O'Brien, but by that time South Africa had more than enough runs to see them into the last eight.