Wales began their Pool D campaign facing a USA side that has tasted considerable success this season and which showed its current form by taking a 10-0 lead with two tries from the experienced Mark Bokhoven.
The Welsh squad, however, quickly showed they meant business as Alex Cuthbert raced in for a fine try converted by Rhys Jones to trail 10-7 at the break.
Wales began the second half looking sharp in attack but it was their pressure defence that undid USA and opened the way for a try by Ifan Evans and a 12-10 lead. The relentless Welsh pressure than produced a third score, this time a try for Rhys Jones who added the conversion to give Wales a 19-10 victory.
Having seen Scotland defeat Fiji, Wales had hopes of a similar win over the pacific islanders in their second tie. But it was not to be. Fiji, looking more dynamic than in their game against Scotland built up a 19-0 half-time lead with tries Seremala Burotu and Ilai Tinai (2) aided by some less than tight Welsh defence.
Wales looked more positive after the break and opened with a try by Ifan Evans converted by Rhys Jones but Fiji hit back with a touchdown from Jack Prasad to make it a 26-7 win for the former world champions.
That left Wales looking for a win over the hosts, Scotland, in the final tie of the first day. In the event it was Scotland who got off to the better start with a converted try for John Houston, but a chip and chase try by Lee Rees after a quickly taken line-out and the conversion levelled the scores.
Scotland then regained the lead with a converted try by Roddy Grant quickly followed by a third Scottish score from Colin Shaw, again converted by Laidlaw, for a 21-7 half time advantage.
Wales began the second half disastrously with a faulty kick-off. Then, after a collision, Lee Beach was forced to leave the pitch and, in a third mishap, Ifan Evans was carded for an off-the-ball offence. With Wales down to six men, Scotland profited with a try from Ben Cairns but Wales showed their grit with a converted touchdown from replacement Alex Walker.
But any hopes of a Welsh fightback were crushed as Grant ran in under the posts. Walker grabbed a consolation score in the dying seconds to make the final score 33-21.
"We made too many errors in all our matches. Against Fiji we had three turnovers and they scored off each one. And against Scotland, we made errors at the kick-off. You can't kick short twice in a tie" said John.
Wales Sevens squad : Jevon Groves (captain, Cross Keys), Rhys Shellard (Cardiff), Ifan Evans (Llandovery), Craig Hill (Newport), Lee Beach (London Welsh), Lee Rees (Scarlets Academy), Alex Walker (Dragons), Rhys Webb (Ospreys), Rhys Jones (Cornish Pirates), Gareth Davies (Cardiff), Lloyd Williams (Blues), Alex Cuthbert (UWIC)
Pool A Samoa 42 Kenya 5, Argentina 5 France 14, Samoa 38 France 26, Argentina 26 Kenya 14, Kenya 7 France 28 , Samoa 10 Argentina 31
Pool B New Zealand 57 Russia 0, South Africa 49 Italy 5, New Zealand 52 Italy 0, South Africa 19 Russia 7, Russia 24 Italy 12 , New Zealand 24 South Africa 17
Pool C Australia 14 Canada 0, England 17 Portugal 5, Australia 35 Portugal 21 , England 19 Canada 26, Canada 14 Portugal 24, Australia England
Pool D USA 10 Wales 19, Fiji 14 Scotland 31, USA 12 Scotland 33, Fiji 26 Wales 7, USA 12 Fiji 24, Wales 21 Scotland 33
Cup quarter finals
Samoa v South Africa, Australia v Fiji, Scotland v England, New Zealand v Argentina
Bowl quarter finals
France v Italy, Wales v Canada, Portugal v USA, Kenya v Russia