EPCR: Refs for Rounds 1 & 2
There are 40 clubs taking part in the two competitions, all of them there through stipulated qualification criteria. 40 teams means 20 matches.
The first match is at Challenge Cup encounter between Pau and Gloucester at Stade du Hameau on the night of Thursday, 12 October 2017. The man to blow the whistle to set Europe's big club competitions in motion is George Clancy of Ireland.
The first Champions Cup match will be in Friday, 13 October 2017 between Saracens, title-holders in 2016 and 2017, and Northampton Saints at Franklin's Gardens. The referee to start that match is France's Pascal Gaüzère who refereed the Rugby Championship match between the Pumas and the Springboks in Salta.
Also in Round 1 is a clash between Top 14 champions Clermont and the Osprey. Andy Brace of Ireland will referee that.
England's premiership winners, Exeter Chiefs, will play Glasgow Warriors at Alexandre Ruiz to see fair play.
There will be another champion in action – the Scarlets who won this year's PRO12. They play Toulon in Toulon with Luke Pearce of England to referee the match.
The competitions end on 11 and 12 May 2018 with finals to be played in Spain – at the San Mamès Stadium over the French border in Bilbao in the land of the Basques.
The appointments are made by a selection committee whose chair man if Joël Jutge, the former Test referees who was in charge of World Rugby's referees for a while.
Match Officials
Round 1
Champions Cup
Ulster vs Wasps at Kingspan Stadium
Referee: Ben Whitehouse (Wales)
Leinster vs Montpellier at RDS
Referee: Wayne Barnes (England)
Racing 92 vs Leicester Tigers at Yves du Manoir
Referee: John Lacey (Ireland)
Harlequins vs La Rochelle at The Stoop
Referee: Marius Mitrea (Italy)
Bath vs Benetton Treviso at the Rec
Referee: Mike Adamson (Scotland)
Exeter Chiefs vs Glasgow Warriors at Sandy Park
Referee: Alexandre Ruiz (France)
Castres vs Munster at Stade Pierre Fabre
Referee: Matthew Carley (England)
Toulon vs Scarlets at Stade Félix Mayol
Referee: Luke Pearce (England)
Northampton Saints vs Saracens at Franklin's Gardens
Referee: Pascal Gaüzère (France)
Ospreys vs Clermont at Liberty Stadium
Referee: Andrew Brace (Ireland)
Challenge Cup
Pau vs Gloucester at Stade Du Hameau
Referee: George Clancy (Ireland)
Enisei-STM vs Bordeaux-Bègles at Krasny Yar Stadium
Referee: Craig Maxwell-Keys (England)
Cardiff Blues vs Lyon at Cardiff Arms Park
Referee: Frank Murphy (Ireland)
Sale Sharks vs Toulouse at AJ Bell Stadium
Referee: David Wilkinson (Ireland)
Agen vs Zebre at Stade Armandie
Referee: Ian Tempest (England)
Krasny Yar vs Stade Français at Krasny Yar Stadium
Referee: Ian Davies (Wales)
Newcastle Falcons vs Dragons at Kingston Park
Referee: Pierre Brousset (France)
London Irish vs Edinburgh at Madejski Stadium
Referee: Dan Jones (Wales)
Worcester Warriors vs Brive at Sixways Stadium
Referee: Seán Gallagher (Ireland)
Oyonnax vs Connacht at Stade de Genève
Referee: Tom Foley (England)
Round 2
Champions Cup
Scarlets vs Bath at Parc y Scarlets, Llanelli
Referee: Romain Poite (France)
Glasgow Warriors vs Leinster Tigers at Scotstoun Stadium
Referee: Jérôme Garcès (France)
Clermont vs Northampton Saints at Stade Marcel-Michelin
Referee: Ben Whitehouse (Wales)
Benetton Treviso vs Toulon at Stadio Comunale did Monigo
Referee: Matthew Carley (England)
Leicester Tigers vs Castres at Welford Road
Referee: George Clancy (Ireland)
Munster vs Racing 92 at Thomond Park
Referee: JP Doyle (England)
Saracens vs Ospreys at Allianz Park
Referee: Marius Mitrea (Italy)
Montpellier vs Exeter Chiefs at Altrad Stadium
Referee: John Lacey (Ireland)
La Rochelle vs Ulster at Stade Marcel-Deflandre
Referee: Nigel Owens (Wales)
Wasps vs Harlequins at Ricoh Arena
Referee: Mathieu Raynal (France)
Challenge Cup
Gloucester vs Agen at Kingsholme
Referee: Dan Jones (Wales)
Brive vs Oyonnax at Stade Amédée-Domenech
Referee: David Wilkinson (Ireland)
Lyon vs Sale Sharks at Matmut Stadium de Gerland
Referee: Mike Adamson (Scotland)
Toulouse vs Cardiff Blues at Stade Ernest Wallon
Referee: Tom Foley (England)
Enisei-STM vs Dragons at Slava Stadium
Referee: Ian Tempest (England)
Krasny Yar vs Edinburgh at Fili Stadium
Referee: Thomas Charabas (France)
Zebre vs Pau at Stadio Sergio Lanfranchi
Referee: Craig Maxwell-Keys (England)
Connacht vs Worcester Warriors at The Sportsground
Referee: Ian Davies (Wales)
Bordeaux-Bègles vs Newcastle Falcons at Stade Chaban-Delmas
Referee: Frank Murphy (Ireland)
Stade Français vs London Irish at Stade Jean-Bouin
Referee: Vlad Iordachescu (Romania)