Newport Gwent Dragons have the consolation of a good draw in Pool 1 for their first foray into the European Challenge Cup.
Gloucester celebrate winning last season's European Challenge Cup
The Welsh region missed out on the top European tier of the Heineken Cup after losing a play-off to Overmach Parma.
But the draw has handed them home and away derbies against English side Bristol, plus ties with Bayonne of France and Bucuresti of Romania.
The first round will be played on the weekend beginning 20 October.
Each of the teams in the five pools is guaranteed six group-stage matches, with the five pool winners and three best runners-up advancing to the knock-out stages.
West Country side Bristol have a long history of matches with sides just across the Severn Bridge.
Bristol coach Richard Hill is a former head coach at Rodney Parade, while they have several Welsh players in their side.
They include fly-half Jason Strange, ex-Cardiff Blues and Wales wing Craig Morgan, plus Wales record cap holder Gareth Llewellyn.
The Dragons themselves can boast players such as Wales Grand Slam stars Michael Owen, Gareth Cooper and Ceri Sweeney.
They have also been bolstered by the signing of fly-half Mike Hercus from Llanelli Scarlets and fellow USA Eagles back Paul Emerick from Overmach Parma.
Pool 1: Newport Gwent Dragons, Bayonne, Bristol Rugby, Bucuresti.
Pool 2: Glasgow Warriors, Narbonne, Saracens, GRAN Parma.
Pool 3: Newcastle Falcons, Brive, Petrarca Padova, Montauban.
Pool 4: Connacht Rugby, Montpellier, Bath Rugby, NEC Harlequins.
Pool 5: ASM Clermont Auvergne, Worcester Warriors, Viadana, Albi.