Six tough encounters await Connacht as they renew acquaintances with Brive and Worcester and face Oyonnax for the first time.
The four previous meetings with Brive saw Connacht pick up one win while they have beaten Worcester Warriors twice at the Sportsground and lost on both visits to Sixways.
Brive finished eighth in the Top14 last season and were knocked out at the quarter-final stage of the Challenge Cup while Oyonnax captured the Pro D2 title.
Worcester battled their way to an 11th place finish in the Premiership and were beaten twice by Brive in the pool stages of last year’s competition.
The five pool winners and three best-placed runners-up qualify for the quarter-finals.
2017/18 Challenge Cup pools
Pool 1: Newcastle Falcons, Newport Gwent Dragons, Bordeaux-Bègles, Enisei-STM
Pool 2: Cardiff Blues, Sale Sharks, Lyon, Toulouse