London - Reigning champions Saracens face the toughest defence of their European Champions Cup title after they were drawn on Thursday with beaten finalists Clermont.
Saracens beat Clermont 28-17 in last season's final before the French club rebounded to claim the Top 14 title.
Joining them in Pool 2 will be Northampton and Ospreys.
Saracens crashed in the semi-finals of the English Premiership playoffs, Exeter going on to win the league.
Exeter were drawn in Pool 3 alongside Montpellier, Leinster and Glasgow, while Racing 92 were pooled with Munster, Leicester and Castres in Pool 4.
Beaten English finalists Wasps were included in Pool 1 with La Rochelle, who finished leaders of the Top 14 at the end of the regular season, Ulster and Harlequins.
Celtic League champions Scarlets drew French giants Toulon, Bath and Treviso, the traditional whipping boys from Italy, in Pool 5.
The five pool winners and three best-placed pool runners-up qualify for the knock-out phases, with the final to be held in the northern Spanish city of Bilbao.
Pool 1: Wasps (ENG), La Rochelle (FRA), Ulster (IRL), Harlequins (ENG)
Pool 2: Clermont (FRA), Saracens (ENG), Ospreys (WAL), Northampton (ENG)
Pool 3: Exeter (ENG), Leinster (IRL), Montpellier (FRA), Glasgow (SCO)
Pool 4: Munster (IRL), Racing 92 (FRA), Leicester (ENG), Castres (FRA)
Pool 5: Scarlets (WAL), Toulon (FRA), Bath (ENG), Treviso (ITA)
Calendar for 2017/18 season:
1st round: October 13/14/15
2nd round: October 20/21/22
3rd round: December 8/9/10
4th round: December 15/16/17
5th round: January 12/13/14
6th round: January 19/20/21
Quarter-finals: March 30/31, April 1
Semi-finals: April 21/22
Final: May 12 at Bilbao