An improved performance in the first half showed what Scotland can do but South Africa ultimately increased the gas in this second pool D game for both sides, to make the final score 20-5, and two defeats from two games for the Scots.
A well-worked first half try from John Houston brought the crowd to its feet but here were few further flashes of flair to cause the same reaction as the game progressed.
The second half did spell a Scotland 7s debut for Rory Hughes who enjoyed his first five minutes of international action.
It's was a visibly more pumped up side that took to the pitch for this second pool game with the game evenly balanced for the first two minutes with a promising reak from Fleming until turnover ball gave du Preez the chance to seize the gap and cross for South Africa. His conversion attempt pulled wide and also caused him to pull a muscle, causing his departure from the game (5-0).
A minute later and a stunningly simple break from John Houston had his tacklers try to take him down just short of the line; dogged determination saw him hang on and lunge across the whitewash to even the scores (5-5).
It was all square for the bulk of the remainder of the half until, just as the hooter cranked up, Kyle Brown dotted down for South Africa, the conversion attempt wide.
Half time: South Africa 10 - 5 Scotland
It was all South Africa at the begnning of the second half, however, as Ulengo bolted for the line twice in the next three minutes, Houston making a valiant attempt to prevent the second try (20-5).
It was a Scotland 7s' debut for Rory Hughes, however, two minutes into the half and he worked well to make his presence felt.
The Scots picked up the pace as the minutes ticked down. A solid run down the wing from Michael Fedo showed promise but with no-one in support it was another missed opportunity and the game ended 20-5.
Scotland 7s v South Africa, Pool D, Twickenham
1 Scott Riddell
2 Michael Fedo
4 Sean Kennedy
5 Colin Gregor
9 Adam Ashe
11 James Fleming
12 John Houston
3 Ross Miller
6 Rory Hughes (used - Scotland 7s debut)
7 Andrew Turnbull (used)
8 Byron McGuigan (used)
10 Andrew Skeen
Referee: James McPhail (NZ)