Paul John's side claimed a famous scalp by defeating Fiji 22-19 in their crunch Pool C decider, Llandovery winger Chris Knight inspiring Wales to a famous victory.
After an opening win over Portugal was followed by a narrow defeat to Canada, Wales knew it was all or nothing against Fiji if they were to reach the last eight of the Cup competition.
And with the pressure on, they stepped up to the plate at exactly the right time. Knight was the catalyst, his two tries proving crucial with James Davies and skipper Adam Thomas also crossing. Fiji had scored three tries themselves, including one with the final play of the game, but it was not enough to prevent a Welsh win.
The victory over Fiji had started worryingly for Wales, Cardiff man Will Thomas stretchered off after a sickening clash of heads with Benito Masilevu. After play had been delayed for a lengthy period of time while Thomas received treatment, Davies gave Wales a 5-0 lead before Masilevu showed his pace to level things up. Osea Kolinisau then exchanged tries with Knight but with Fiji crucially down to six men after Vuniani Vucago Bainitabua was yellow carded, Wales held the upper hand at the break despite being two points behind.
The second half saw Wales play some superb sevens rugby. Debutant Adam Field looked like he would put his side back in front, only for some superb Fiji defence to knock the ball from his grasp as the try line beckoned. Wales refused to be rattled though and Knight showed a devastating turn of foot to cross for his second.
And when Adam Thomas added Wales' fourth following a superb Davies turnover, Wales knew a quarter final berth was theirs. Sakiusa Nadruku crossed late on for Fiji but it was merely a consolation try.
Earlier in the day, Wales had started with a comfortable 33-14 victory over Portugal. Pontypridd speedster Alex Webber got things going with the opening score after just over a minute. Will Thomas had added the conversion but Wales struggled in the rest of the first period as Pedro Leal guided Portugal into a 14-7 half time lead.
That was as good as it got for them though as Wales ran riot after half time. Rhys Shellard got things moving before tries from Adam Thomas and Field gave Wales complete control. There was still time for a late finish from Knight as Wales began their campaign in Australia with a win.
After a solid start, Wales then received a setback as a slow start saw them beaten 19-14 by Canada. A trip to the sin bin after just 33 seconds for the hugely experienced Shellard left Wales a man light, leaving their opponents to take advantage.
A brace of tries from John Moonlight gave Canada a 12-0 lead at the break, Connor Braid converting the first of those scores as Wales struggled to get going.
The second half was a different story as tries from Knight and Davies saw Wales come roaring back into the equation. Will Thomas had added both sets of extras but with Canada crossing for their third score right at the start of the second half, it proved enough to send Wales to defeat.
It left them needing to beat Fiji to reach the latter stages of the Cup competition but after doing just that, and in impressive fashion too, they will take on South Africa tomorrow in more than confident mood.