"The win in Wellington gave the boys a great belief in themselves. But that's still a fantastic result. To beat New Zealand twice in three weeks is a huge boost for Welsh sevens," said a delighted John.
"All 10 players that we used were outstanding," concluded John.
The omens weren't good in the opening minute when Wales turned over possession for the lanky Zac Lawrence to run round under the posts for a converted try but the Scarlets scrum-half immediately hit back with an individual piece of magic.
He plucked the ball from a ruck and ran 60m down the touchline before standing up Nigel Hunt with a swivel of the hips to race home.
New Zealand lost their ruthlessness as Wales took the game to them and the men I red hit the front for the first time in the match as the halftime hooter sounded. Williams took a quick tap and made room for Richie Pugh who finished wide out to give Wales a 10-7 lead.
The Kiwis hit back when Lote Raikabula sped to the line from 50m to regain the lead at 14-10 but Wales continued to pressure New Zealand into uncharacteristic mistakes. The top seeds looked to have wrapped it up in the dying stages but Viliame Waqaseduadua inexplicably dropped the ball after gathering and having the try-line at his mercy.
With just 60secs to go replacement Tom Isaacs stunned New Zealand when he hacked through a pass from Pugh to send the favourites crashing out.
Wales now face the big hitting Samoans in the semi-finals as they attempt to reach the final later this afternoon.