Champions Trophy, Ahmedabad: South Africa 219-9 (50 overs) bt Sri Lanka 141 (39.1 overs) by 78 runs
Pollock had a hand in three of the five Sri Lankan wickets
South Africa kept their Champions Trophy hopes alive with a 78-run victory over Sri Lanka in Ahmedabad.
Graeme Smith's side made 219-9 after being put into bat, with AB de Villiers scoring 54 and Jacques Kallis 43.
And they then dismissed Sri Lanka for 141 in reply as their disciplined pace attack did all the damage.
South Africa need to beat Pakistan to be sure of qualifying for the semi-finals, but Sri Lanka's Trophy hopes now hang by a thread.
They need Pakistan to win their remaining two games and would still only progress if their run-rate was superior to South Africa or New Zealand.
Sri Lanka appeared strong favourites after restricting South Africa to what looked like a modest total at the Sardar Patel Stadium.
The Proteas were 30-3 at one stage before De Villiers, in for Andrew Hall, and Kallis steadied the ship.
They put on 80 for the fourth wicket, despite Kallis needing treatment for an ankle injury, but struggled to find any fluency against some tight bowling.
It was only some lusty hitting from Shaun Pollock (21 not out from 17 balls) and Robin Peterson (22 from 16) in the last few overs that carried them beyond the 200 mark.
Chaminda Vaas was the pick of the Sri Lankan bowlers in terms of accuracy with 2-16 from 10 overs, while Lasith Malinga finished with 4-53 from nine.
In reply, Sri Lanka were 34-4 at one stage, with Sanath Jayasuriya (3), Upul Tharanga (11) and Kumar Sangakkara (0) all falling cheaply.
And when skipper Mahela Jayawardene (36) was brilliantly run out by a combination of Herschelle Gibbs and Pollock, the game looked up.
Tillakaratne Dilshan (36) and Chaminda Vaas (29 not out) offered some resistance, but Sri Lanka never looked like reaching their target.
Pollock (2-21) was superb for South Africa, while Makhaya Ntini (2-24) and Andre Nel (3-41) also played their part.
In the remaining Group B games, New Zealand play Pakistan on Wednesday while South Africa play Pakistan on Friday.