In reply to Sri Lanka 'A' total of 238 in 49.4 overs, the South Africans reached the required runs with utmost ease 242 for 3 in 40.1 overs.
Centurion Jaarsveld had good support from Derek Crookes (60) and the second wicket pair added 90 runs. Crookes faced 80 balls with four boundaries and Jaarsveld remained unbeaten on 121. He had faced 111 balls with 14 fours, a five and two sixes.
Earlier Sri Lanka 'A' were all out for 238. Left-hander Avishka Gunawardena top scored with 46, facing 94 balls with four boundaries. Gunawardena added 40 for the third wicket with Indika de Saram. But it was Ruchira Palliyaguru and wicketkeeper Lanka de Silva who helped the side reach the 200 run-mark with a 70-run stand for the sixth wicket.
Palliyaguru struck a couple of fours and sixes and faced 29 balls in his 36 and Lanka de Silva had two fours and faced 46 deliveries in his 30.
Pacemen Claude Henderson and Alan Dawson took two wickets apiece for the visitors.
The final one day game will be played today at the SSC grounds.