Of the eight fixtures in which Irish, Scottish and Welsh teams took on foreign opposition, teams from the Magners League came out on top six times.
Munster, Glasgow, Ulster, Cardiff Blues and the Ospreys all secured Heineken Cup wins over opposition from other leagues, while Connacht claimed a superb Challenge Cup triumph at Worcester Warriors.
Munster and the Blues beat French giants Perpignan and Toulouse respectively and will now hope for of the same in the return matches next weekend.
Ronan O'Gara was the Munster hero as he kicked all 24 points in the reigning Magners League Champions' victory over the current Top 14 Champions, while Ben Blair was similarly impressive with the boot in the Blues' 15-9 win over three-times European Cup winners Toulouse.
Ulster produced a stunning performance to end the unbeaten Heineken Cup run of Parisian aristocrats Stade Francais at Ravenhill and the Ospreys ran in eight tries in a 62-7 thumping of Viadana on Italian soil.
Magners League leaders Glasgow Warriors carried on where they left off in Celtic competition with a comfortable 33-11 win over Gloucester at Firhill as they bounced back from previous European defeats to Biarritz and the Dragons.
In an all-Magners League tie in Llanelli, European Champions Leinster crushed the Scarlets 32-7 to make things very interesting at the top of Pool 6 where the Scarlets and London Irish are also in contention for a quart-final place.
The only Magners League sides to taste defeat against foreign outfits were Edinburgh and the Dragons, both of whom lost away from home to Bath and Biarritz respectively.
Heineken Cup results involving Magners League teams
Munster 24 Perpignan 23
Glasgow Warriors 33 Gloucester 11
Ulster 23 Stade Francais 13
Viadana 7 Ospreys 62
Cardiff Blues 15 Toulouse 9
Scarlets 7 Leinster 32
Bath 16 Edinburgh 9
Biarritz 49 Newport Gwent Dragons 13
Amlin Challenge Cup results involving Magners League teams
Worcester Warriors 21 Connacht 26
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland