Holders Saracens will face a tough pool in defence of their Heineken Champions Cup crown next season.
The European and Premiership title holders were drawn in the same group as Munster – the team they beat in last season’s semi-finals – Racing 92 and Ospreys.
The blue riband European tournament also sees Premiership runners-up Exeter grouped with Glasgow – their new star signing Stuart Hogg’s former club – Sale Sharks and La Rochelle.
Danny Cipriani’s Gloucester, meanwhile, were pooled alongside French champions Toulouse, Connacht and Montpellier at Wednesday’s draw in Lausanne.
Premiership rivals Bath and Harlequins will contest Pool Three with Clermont Auvergne and Ulster, and four-time European champions Leinster are joined in Pool One by Northampton, Lyon and Benetton.
Leicester will face Cardiff Blues, Pau and Calvisano as their pool stage opponents in next season’s European Challenge Cup.
The Tigers failed to qualify for the Champions Cup following a dismal Premiership season when they finished one place above relegated Newcastle.
Elsewhere, Leicester’s fellow former European champions Wasps were grouped with Edinburgh, Bordeaux-Begles and Agen, while newly-promoted Premiership club London Irish will tackle a testing pool that also features Scarlets, Toulon and Bayonne.
New Dragons boss Dean Ryan will face an appointment with one of his former clubs Worcester in Pool One, and Pool Four sees Bristol facing French threats from Stade Francais and Brive.
The group stages of both tournaments begin in mid-November, two weeks after the Rugby World Cup final.