Cardiff's Casey Laulala carried the good form he showed against Connacht into Saturday's win over Edinburgh as he notched the game's decisive try.
Edinburgh took a deserved early lead when Chris Paterson scored a penalty, before prop Allan Jacobsen barged his way over. Paterson added the conversion to give the Scots a 10-0 advantage.
Dan Parks had an off-day with for the Blues as he missed a total of six kicks at goal, but the home side held on for a one-point win.
On Friday night, a try within 27 seconds of the restart swung the game in favour of Northampton Saints in their clash with Castres, who took an 8-5 lead in at the break. But full-back Ben Foden struck for the crucial try as Northampton held on.
Saracens' excellent domestic form deserted them as Clermont outscored their English opponents by three tries to one, with Jamie Cudmore, Julien Malzieu and Napolioni Nalaga all touching down for the hosts.
Leinster took a bonus-point win over Racing Metro, with Jamie Heaslip adding the fourth try, though Brian O'Driscoll's hamstring injury was the downside of an otherwise excellent day.
Toulon marked their first appearance in the competition with a win over the Ospreys, with English men providing all the points.
Paul Sackey got the decisive try after Shane Williams looked as though he had given the Welsh side the win when he touched down on the hour mark.
Jonny Wilkinson kicked 14 points and the out-half landed a 74th-minute sideline penalty before his pass put Sackey away in the corner for a famous win.
David Wallace and Ronan |O'Gara were heavily involved in the late move that put centre Sam Tuitupou through for the try that secured a crucial losing bonus point for Munster against London Irish.
The Scarlets beat French giants Perpignan in a nine-try spectacular at Parc y Scarlets. Wales out-half Stephen Jones scored 28 points for the home side, including a try. Perpignan clawed their way back from 40-15 down after 50 minutes to claim a try bonus point.
However, Jerome Porical missed with a last-minute penalty that would have earned a second losing bonus point.
Six David Skrela penalties gave reigning champions Toulouse an 18-16 win over Wasps in France yesterday. But the English side would have walked away with a stunning victory if it hadn't been for David Walder's late miscue from a penalty. David Lemi touched down for Wasps.
Hooker Fergus Thomson scored Glasgow's second try against the Dragons to pave the way for a Warriors victory for the first time on the opening weekend since 1997. Graeme Morrison also touched down for the home side, with Adam Hughes going over for the Dragons.