Llanelli Scarlets were the first of the Celtic Rugby squads in action when they ran in a 95-0 win against Slovenia's national side at Ljubljana on August 7.
The Scarlets scored 14 tries with former Wales under 19 fly half Ceiron Thomas ending up with 25 points.
Director of rugby Gareth Jenkins was pleased with his players and said: "They showed they were up for the challenge in the absence of many of our international players. It was an essential part of our preparation and these youngsters have a big part to play in our Celtic League and Celtic Cup campaign this season."
Lee Byrne led the way with a hat-trick of tries, while among the other try scorers were Gavin Quinnell (younger brother of Scott and Craig), skipper Tal Selley, Dale Burn, Aled Gravelle, Barry Davies, Jonathan Lewis and replacement Garan Evans.
London Welsh provided the opposition for the new Celtic Warriors squad as they appeared on the Metropolitan Police ground at Imber Court with coach Lynn Howells content with the start.
Prop Phil Booth (2), wing Paul Jones and full back Matthew Nuthall scored the tries for the Warriors and Howells summed it up with: "It was great to see supporters there from Pontypridd and Bridgend and to hear the chant of 'Warriors' was a good sign for the future. Long may it continue."
Edinburgh Rugby played well in the tight, but were not so good out wide, as they lost to Zurich Premiership newcomers Rotherham 40-26 in an away match, being without 10 first-string players. The match was played over three sessions and Rotherham led 19-12 after the first session when David Callum and Allan Jacobsen scored the Edinburgh tries.
In the other sessions hooker Andrew Kelly and his replacement Douglas Hall went over with Ander Monro supplying the conversion points. Todd Blackadder led the squad with 23 players being used.
Glasgow Rugby began their warm-up with a 28-12 loss to Gloucester at Kingsholm on a night of four periods with Gloucester leading 8-0 after the first, still being ahead at 11-7 after the second and going further in front at 21-7 after the third period.
New coach Hugh Campbell found out that "we did not have enough possession, but when we did, we were dangerous and our defence was outstanding."
Colin Shaw, a full back borrowed from Glasgow Hawks, scored the first Glasgow try and fly half Calvin Howarth converted. In the final session, young centre Graeme Morrison went over after collecting a kick to the corner by co-centre Gareth McClure.
The Borders did kick-off with a win, albeit by 47-5 at Mansfield Park, Hawick, against a Border League XV, but coach Tony Gilbert stated: "It was a very useful exercise and it was a competitive game against a competitive team."
It was 28-5 at the interval after Borders had scored tries by Clark Laidlaw, Stephen Cranston, Gareth Morton and Cammie Murray and Murray went on to complete a hat-trick with Paul Thomson also crossing. The latter converted the first four before Calum MacRae added another two.
In Wales. Neath-Swansea Ospreys began with a 42-0 romp at the Lewis Lloyd Ground against Division One club Narberth. Some of the big guns of the Ospreys were available and internationals Shane Williams (2) and skipper Scott Gibbs were among the try-scorers.
A crowd of 1,500 witnessed a flowing match that saw the Ospreys lead 30-0 at the interval with Shaun Connor, James Storey, Adrian Durston, Gareth Swales and Gareth Morris gaining the other tries and Connor landing one conversion.
Coach Lyn Jones said: "We cannot wait to entertain the likes of Munster and Edinburgh at the Gnoll and St Helen's. The squad has come together incredibly well and our new training facilities are superb."
Gwent Dragons marked their arrival with a crushing 53-8 victory at Penzance, the Pirates letting in scrum half Bryan Shelbourne for the first after just 11 minutes and centre Steve Winn finishing with a hat-trick as the Dragons ran away with matters in the second half.
Still to come:
Friday, 22 August
Celtic Warriors v Sale Sharks (Brewery Field); Cardiff Blues v Leicester Tigers (7.05); Gwent Dragons v Leeds Tykes (Pontypool Park, 7.00); Neath-Swansea Ospreys v Worcester (Gnoll, 7.00); The Borders v Exeter (Langholm, 7.00); Glasgow Rugby v Newcastle Falcons (Hughenden); Ulster v Orrell (Ravenhill); Leinster Lions v Gloucester (Donnybrook, 7.30); Munster v Rotherham (Thomond Park, Limerick, 7.00).
Saturday, 23 August
Leinster Lions v Gloucester; 3 club tournament at Doncaster - Celtic Warriors, Doncaster and Wakefield.
Sunday, 24 August
Carmarthen Quins v Llanelli Scarlets.
Monday, 25 August
Gwent Dragons v NEC Harlequins (Rodney Parade, 2.30).
Tuesday, 26 August
Connacht v London Irish (at the Sportsground, Galway).
Friday, 29 August
Cardiff Blues v Northampton Saints (7.05); Llanelli Scarlets v Newcastle Falcons (7.00); Ulster v London Irish (Ravenhill).
Saturday, 30 August
Leeds Tykes v The Borders (2.30); Gloucester v Leinster Lions (Kingsholm).