The South African under-19 cricket team chased down England U-19s 300/5 to win the fifth match of the seven-match England Youth Series at Taunton in Somerset.
Duanne Olivier (22 not out off 12 balls), batting at No10, hit the winning runs with a boundary off the final ball of the game for a one-wicket victory.
The South Africans now lead the series 3-1 with two games left - today and Saturday.
Earlier, England dominated from the start, with Daniel Bell-Drummond (72) and Sam Wood (57) sharing a stand of 113 for the first wicket.
The two departed within two overs of each other, part-time bowler Keaton Jennings collecting both sculps.
But wicketkeeper Sam Kelsall (64) and Aneesh Kapil (54) picked up where the openers had left off with a third-wicket partnership of 118.
A quick-fire 24 from 14 by captain Adam Ball and Peter Burgoyne's 18 off nine guided the English side to the huge total.
South Africa got off to the worst possible start, losing Quinton de Kock to the first ball for nought and the previous match's centurion Gihan Cloete for just three inside five overs.
Captain Jennings fought hard for his 33 before being run out. It was half-centuries by Shaylin Pillay (52) and James Price (58) that steadied the ship.
But the loss of wickets had the visitors in heaps of trouble at 148/6. But 46 off 43 from Calvin Savage and Prenelan Subrayen's 48 from 33 just about took South Africa home before Olivier's big-hitting heroics at the end.
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