Newcastle Falcons took early control of Pool Three with a creditable 30-26 victory at Newport Gwent Dragons.
Lock Will Witty, flanker Mark Wilson and wing Lee Smith helped Newcastle match Newport's three tries, from Matthew Pewtner, Taulupe Faletau and Ashley Smith.
Tom Prydie's two penalties and one conversion, and another penalty goal from Angus O'Brien pushed the Dragons to the brink of victory.
Lee Smith's long-range penalty strike secured a vital win for Dean Richards' side though, who stay top of the pool, with Rory Clegg also posting two penalties and three conversions.
The Falcons backed up their 43-19 victory over Bucharest by denying the Dragons a chance to make it two from two, the Welshmen succumbing after their 38-22 win at Stade Francais the previous week.
London Irish maintained their 100 per cent record with a four-try, bonus-point victory at Grenoble to stay top of Pool One.
The Exiles won out 25-15 thanks to tries from Shane Geraghty, Halani Aulika, Alex Lewington and Luke Narraway.
La Rochelle opened up Pool Two with a 25-13 victory over Bayonne to register their first points of the European campaign.
Julien Berger, Levani Botia and Jone Qovu Nailiko crossed for La Rochelle, with wing Pierre Sayerse claiming Bayonne's sole score and Blair Stewart slotting two penalties.
Brive compounded their 55-point thrashing at Gloucester in round one with a dispiriting 26-21 home defeat to Italians Zebre.
Edoardo Padovani's 16 points with the boot proved to be the difference, with Brive slipping up despite outscoring their visitors by three tries to two.
Kelly Haimona and Valerio Bernabo crossed for Zebre, with Rian Swanepoel, Andrew Mailei and Thomas Sanchou's scores for Brive receiving the solitary losing-bonus reward.
Edinburgh racked up their second straight win by edging out Lyon 25-17 at Murrayfield.
Tom Heathcote's 20-poinnt haul with the boot proved pivotal, with Jack Cuthbert claiming the hosts' only try.
Masi Matadigo and Mickael De Marco hit back for the Frenchmen, but Edinburgh clung on, denying the visitors even the losing bonus.