Northampton face a tough return to European rugby when they launch their Challenge Cup campaign in October.
The Saints, who regained Premiership status after winning last season's National League One title, will visit big-spending French outfit Toulon on October 9.
Toulon, newly promoted to the Top 14 in France, recently enhanced a galaxy of playing talent by recruiting former New Zealand All Blacks flanker Jerry Collins and South Africa international Joe van Niekerk.
Other highlights of the opening weekend see Bristol visiting Montpellier, whose summer signings include ex-England centre Ollie Smith and New Zealand scrum-half Justin Marshall, while Saracens host French side Stade Montois.
The three other English challengers all face favourable starts, with last season's Challenge Cup runners-up Worcester visiting Italian outfit Petrarca, London Irish entertaining Rovigo and Newcastle hosting Spanish minnows El Salvador.
Each of five pool winners and the three best runners-up will qualify for the quarter-finals.
The RBS 6 Nations Championship 2015 was not poised to go down as one of the more "vintage" Championships, though there was great anticipation as the action headed into its final day. What transpired was something that nobody could foresee: "The Greatest Day in Rugby's Greatest Championship."