Saracens, last season's winners of an historic Champions Cup and Premiership double, will start their 2016/17 European campaign at Toulon.
A truly heavyweight clash against the three-time champions will take place at Stade Félix Mayol on Saturday, October 15.
The Anglo-French Pool 3 match is just one of numerous high-profile confrontations in the fixtures scheduled for Rounds 1 to 4 of this season's Champions Cup and Challenge Cup which were announced by tournament organisers EPCR.
Connacht, who captured the PRO12 title in magnificent style last season, will be guaranteed a full house at the Sportsground for the Round 1 visit of four-time tournament winners, Toulouse, also on Saturday, October 15, while last season's Top 14 champions, Racing 92, host Munster under new director of rugby, Rassie Erasmus, at Stade Yves-Du-Manoir on Sunday, October 16.
2016 Challenge Cup winners, Montpellier, kick-off their European season with a demanding Pool 4 fixture against Northampton Saints at Franklin's Gardens on Saturday, October 15.
Scarlets, who were drawn in the ultra-competitive Pool 3 with Saracens, Toulon and Sale Sharks, open up against Sale at Parc y Scarlets on the same Saturday.
Toulouse are moving their mouth-watering Round 2 game against Wasps to Le Stadium on Sunday, October 23, and Leinster will attract another big attendance for the Round 4 visit of the Saints to the Aviva Stadium on Saturday, December 17.
Bristol make their return to European competition for the first time since the 2008/09 season when they take on old rivals, Cardiff Blues, in Round 1 of the Challenge Cup at Ashton Gate on Friday, October 14.
Newcomers, Timisoara Saracens of Romania, are in Pool 5 action against Edinburgh at the Dan Paltinisanu Stadium on Saturday, October 15.
What promises to be an epic journey to the 2017 finals weekend at Edinburgh's Murrayfield Stadium begins with the Challenge Cup head-to-head between European stalwarts Harlequins and Stade Francais Paris at the Twickenham Stoop on Thursday, October 13.
The dates, kick-off times and TV coverage for the Round 5 and 6 fixtures in both tournaments will be announced in December following the completion of the Round 4 matches.
Fixtures in full