Rangana Herath picks six as Sri Lanka wins by 199 runs to complete 2-0 sweep
Chasing an improbable 490-run victory target, South Africa showed some fight in the morning session before losing their final five wickets and being all out for 290.
Theunis de Bruyn top scored for South Africa with a gutsy 101 in yet another batting capitulation by the leaden-footed tourists who lost all 10 wickets to the Sri Lankan spinners for the second time in the match.
Rangana Herath was pick of the Sri Lankan bowlers, claiming 6-98 in yet another spin-dominated performance by the hosts.