"It's been a great day to be fair," said head coach Paul John. "When we looked at the group before we came out here every side would have thought they had a great chance to make it out of the group. Fortunately we have but now we have got to back that up.
"The boys put in a great performance but the challenge now is to back it up. We will have to regroup and recharge the batteries for tomorrow."
Llandovery speedster Chris Knight has raced to the top of the try scoring charts, having now scored nine tries in the first two legs of the HSBC Sevens World Series to share the lead with New Zealand star Tim Mikkelson.
Wales over ran Spain in the opening game scoring six tries with Knight leading the way with a brace. Thomas, James Davies, Lee Williams and Luke Morgan completed the rout with Rhys Jones adding the remaining points with his left foot.
Scotland proved a sterner test with Wales racing out to an early 14-0 lead with converted tries by Ashley Evans and Davies who scored the try of the day, showing dazzling footwork more suited to Strictly Come Dancing, to waltz over from 50m.
The Scots hit back and led early in the second half when captain Colin Gregor scored in the corner but Knight and Morgan touched down to ease Welsh nerves to earn a hard fought win.
Wales went into the final pool game against Australia knowing a win would ensure a Cup quarter-final.
Knight scorched away for a breakaway try before Australia, finalists in the first leg of the world series on home soil, replied through Lewis Holland who converted his own try.
Rhys jones then burst from scrum, jinked and jived, floated a slide-rule pass to Davies who scooted over from halfway. Jones' conversion put Wales 12-5 ahead but Australia regained the lead with a converted try by Luke Morahan.
With their quarter-final place in jeopardy, Davies picked up the pieces from a dropped Australian pass and raced 50m to score to give Jones an easy match winning conversion.