Edinburgh ended a run of six successive defeats by two-time European Cup winners Munster on Saturday with a 29-23 victory over the Irish province in their opening Pool Five clash.
There was more joy for Leinster, however, the three-time Cup winners battling to a 19-9 victory over Welsh region Ospreys, French champions Castres also recording a close win in the same Pool 1 with their 19-13 victory over Northampton.
A try from Ireland flanker Sean O’Brien converted by Kiwi fly-half Jimmy Gopperth, who also kicked four penalties, was enough for Leinster to scrape past perennial under-achievers Ospreys, for whom Dan Biggar notched up three penalties.
Leinster captain Jamie Heaslip admitted his side had “won the war of attrition”.
“That game could have gone either way,” the No 8 told Sky Sports.
“We’ve got a lot to work on for next week.”
At Murrayfield, Scotland scrum-half Greig Laidlaw was the driving force, kicking 19 points including converting the two Edinburgh tries as they made an impressive start to their campaign.
Munster, who also lost their opening pool match last term, took the consolation of a defensive bonus point in a Pool 6 that saw Gloucester notch up a 27-22 home win over Perpignan.
Edinburgh burst out of the blocks against Munster, opening up a 10-0 lead after just 12 minutes thanks to a try by Matt Scott converted by Laidlaw, who also nailed a penalty.
However, the European heavyweights hit back to level at 10-10 in the 20th minute as Kiwi centre Casey Laulala scored, and was converted by Ian Keatley, who had got them off the mark with a penalty.
Laidlaw booted the hosts back into a 13-10 lead, only for Munster to reply with a close-range try through Mike Sherry, Keatley converting.
However, more ill discipline by Munster saw Laidlaw knock over another two penalties to give the hosts the lead once again at 19-17.
Keatley slotted over a penalty from wide out on the left in the 53rd minute to give the visitors a one point lead, 20-19 and the 26-year-old added another just over 10 minutes later.
However, the hosts went back in front with a fine try by Scotland’s Dutch-born wing Tim Visser, whose electric pace proved too much for the two covering Munster defenders.
Laidlaw continued his faultless day as he converted for 26-23. He then made it seven kicks from seven attempts with just over four minutes remaining to wrap up victory.
Elsewhere, Scarlets recorded their first win in their last six trips to England with a thrilling 33-26 victory over Harlequins.
Scarlets, who endured a torrid European Cup last season with six defeats in pool play, enjoyed a terrific first-half at Twickenham Stoop rounded off in brilliant fashion by an individual try by Scott Williams, who took the ball inside his own half, broke two tackles, dummied Danny Care and touched down.
Rhys Priestland, who had created the first try, converted to send the Welsh side in leading 20-10 at half-time.
Nick Evans reduced the deficit with a drop goal four minutes into the second-half just after Scarlets Samson Lee was sin-binned.
However, Priestland landed two penalties during the 10 minute absence of Lee to give the visitors a 26-13 advantage only for Evans to score two of his own.
The Scarlets’ more enterprising play was deservedly rewarded with another sparkling try in the 63rd minute.
Scott Williams turned the ball over, and when it was fed to Jordan Williams, 30 metres out, the winger darted down the left touchline, breaking two tackles and then cut inside breaking another to touch down.
Priestland, faultless throughout the game, converted for 33-19.
However, Harlequins got right back into it with just over 11 minutes remaining as England fullback Mike Brown scored his second try of the game, Evans converting to bag the invaluable bonus point.
Montpellier put Treviso to the sword, 27-10, in the remaining Pool 5 encounter, Ulster having beaten Leicester on Friday.