Lee Williams heads for the tryline with the South African defence in hot pursuit.
Wales produced the shock of the day to stun South Africa in the Emirates Airlines Glasgow Sevens at Scotstoun Stadium in the penultimate leg of the HSBC World Series.
The boys have been very profressional in their approach to every game. It's important we continue in the same vein tomorrow and have a good second day
Wales had failed to lower the colours of South Africa since the Commonwealth Games in 2006 but in the final pool game of the day, the men in red produced a professional performance to claim their first ever World Series win against South Africa to top their pool with a 17-5 victory.
Captain Rhys Shellard gave Wales the perfect start in the crunch game of the pool, scoring in the second minute. Alex Walker's conversion put Wales 7-0 ahead and only 40 seconds had gone by before Ifan Evans increased the advantage with a clinical finish.
South Africa, looking to close the gap on overall series runners-up Fiji, hit back through Jamba Ulengo just before the break but Tom Grabham, in his debut tournament with Wales, made sure of the breakthrough victory with the only try of the second half to set up a Cup quarter-final against Australia tomorrow.
Wales got their campaign off to a satisfactory 17-14 win over hosts Scotland with Ifan Evans and Lee Williams scoring first half tries. James Fleming, who also scored in the first spell, ensure a few furrowed brows when he scored his second try for the Scots in the second half but Rhys Shellard's try in the last minute eased Wales home.
Wales hit their straps against Russia to record a comfortable 31-5 triumph with Lee Williams racing over for a brace with Shellard, Richard Smith and debutant Sion Bennett scoring the others with Alex Walker adding three conversions.
A delighted Wales Sevens head coach Paul John was beaming with pride after guiding his side to a groundbreaking victory over the fancied South Africans.
"The boys have a huge opportunity now," he said, "The boys were excellent today. We had a really good win against Scotland under difficult circumstances as the home crowd were firmly behind them as you would expect. We then followed that up with a solid win against Russia where we were particularly excdellent in the second half.
"And to then cap that off with our first ever win over South Africa in the world series to top the group was the icing on the cake. The boys have been very profressional in their approach to every game. It's important we continue in the same vein tomorrow and have a good second day. We all know that the boys have a huge opportunity tomorrow."
Nearly 40 players were involved in the first Wales Under 18 training session of the season. WRU National Performance Manager Gethin Watts is excited at the potential shown by the group and expects the Regional Under 18 Championship to hone their skills even further.