An array of Guinness Six Nations stars will be going up against one another this weekend as the Heineken Champions Cup returns.
The European tournament has a different format this season, with clubs separated into tiers based on their respective domestic finishes last time out.
Two 12-team pools have been split into three-team groups from across the tiers, with each club’s fixture list made up of home and away matches against two other sides.
The top four from each pool will contest the quarter-finals, with the teams finishing between fifth and eighth to drop into the European Challenge Cup.
The opening weekend brings some heavyweight clashes, with plenty of internationals on show after starring for their countries during the conclusion of the Guinness Six Nations as well as the inaugural Autumn Nations Cup.
Here’s an overview of what, and who, to look out for this weekend…
Ulster v Toulouse (KO 20:00 UK)
The 2020 Guinness Six Nations Player of the Tournament, Antoine Dupont, will be hoping to take his France form into a Toulouse shirt on the opening night of European competition.
Dupont takes the No.9 jersey in a Toulouse outfit also including Romain Ntamack, who starts at inside centre, and Thomas Ramos, who moves from full-back to fly-half.
They will face a stern test against an in-form Ulster side who are yet to taste defeat this season.
Jacob Stockdale returns from Ireland duty and starts on the wing while Eric O’Sullivan, who made his debut for Andy Farrell’s side last weekend, lines up in the front row.
Also on Friday: Northampton Saints v Bordeaux-Begles (KO 17:30 UK)
A Saints side featuring England’s Courtney Lawes and Wales fly-half Dan Biggar host a Bordeaux XV including Les Bleus flanker Cameron Woki.
Bristol Bears v Clermont Auvergne (KO 13:00 UK)
Buoyed by winning the Challenge Cup last season, Bristol Bears are ready to get stuck into European competitions once more and welcome giants Clermont Auvergne to Ashton Gate.
Recent Wales debutant Callum Sheedy starts at fly-half, while England flanker Ben Earl begins in the back-row.
Clermont’s side includes experienced French half-back pairing Morgan Parra and captain Camille Lopez, along with wing wizard Damian Penaud.
Montpellier v Leinster (KO 17:30 UK)
Arthur Vincent, who made his France debut in the 2020 Guinness Six Nations opener, captains a Montpellier side which also includes Paul Willemse in the second row.
Leinster welcome back their hearty contingent of Irish internationals, with Hugo Keenan, Robbie Henshaw, Josh van der Flier and Caelan Doris in the starting XV after shining at international level over the autumn.
Johnny Sexton is among the replacements along with Ronan Kelleher, Cian Healy and James Ryan.
Also on Saturday: Bath v Scarlets (KO 15:15 UK)
Anthony Watson and Jonathan Joseph are two of five England internationals in the Bath backline. In-form pair Sam Underhill and Taulupe Faletau, of England and Wales respectively, start in the back-row against a Scarlets side featuring an array of Welsh stars, including Leigh Halfpenny, Gareth Davies and Samson Lee.
RC Toulon v Sale Sharks (KO 15:15 UK)
Two French youngsters who have impressed over the autumn, Louis Carbonel and Gabin Villiere, start for a Toulon team captained by Italy legend Sergio Parisse. Sale’s starting XV includes 13-cap England wing Marland Yarde.
Dragons v Wasps (KO 17:30 UK)
Jamie Roberts and Nick Tompkins make up a powerful midfield partnership for Dragons, who return to the competition for the first time in a decade. Joe Launchbury captains a Wasps outfit including recent England debutant Jack Willis.
Edinburgh v La Rochelle (KO 20:00 UK)
Edinburgh are boosted by the return of their wealth of Scotland stars, including one of the finds of the autumn in wing Duhan van der Merwe. France back-rower Gregory Alldritt captains the visitors.
Exeter Chiefs v Glasgow Warriors (Sunday December 13, KO 15:15 UK)
Reigning champions Exeter Chiefs begin their quest to retain the trophy on Sunday afternoon, with Glasgow Warriors the visitors to Sandy Park.
The clash pits Scotland captain Stuart Hogg up against his former club, while he is joined in the Chiefs squad by international teammates Jonny Gray, Sam Skinner and Sam Hidalgo-Clyne.
England ace Henry Slade lines up in midfield while reigning European Player of the Year Sam Simmonds starts at No.8.
Trying to topple the Devonians will be a Glasgow side boosted by the return of their own Scotland contingent, including the Fagerson brothers Zander and Matt.
Racing 92 v Connacht (Sunday December 13, KO 15:15 UK)
Last season’s beaten finalists Racing 92 will hope to go one better this time around and kick off their European campaign against Connacht.
Finn Russell, who missed Scotland’s Autumn Nations Cup campaign through injury, makes his comeback while French flyers Virimi Vakatawa and Teddy Thomas are also part of a supremely talented backline.
Ireland centre Bundee Aki is among the Connacht replacements and Kieran Marmion starts at scrum-half.
Also on Sunday: Lyon v Gloucester (KO 13:00 UK)
Powerhouse Mathieu Bastareaud takes the No.8 jersey for the hosts while Gloucester welcome back 19-year-old scrum-half Stephen Varney, who made his Italy debut in the Autumn Nations Cup.
Munster v Harlequins (KO 17:30 UK)
Experienced Ireland stars CJ Stander, Peter O’Mahony, Conor Murray and Keith Earls start for Munster, who welcome a Harlequins side which includes no shortage of international knowhow in the likes of Joe Marler, Danny Care and Mike Brown.
European Challenge Cup
There will be plenty of Italian stars on show for Benetton and Zebre as they begin their European campaigns against Stade Francais and Bayonne on Friday and Saturday respectively.
Benetton start with Tommaso Allan at fly-half and recent Italy debutant Monty Ioane on the wing, while Johan Meyer and David Sisi line up for Zebre.
England’s Guinness Six Nations-winning trio George Ford, Ellis Genge and Ben Youngs are set to make their first Leicester Tigers appearances of the season from the bench as they welcome Brive on Friday evening.
Shane Lewis-Hughes, who made a strong introduction to international rugby for Wales over the autumn, is in the Cardiff Blues side heading to Newcastle Falcons on Friday, while George North and Justin Tipuric start for Ospreys against Castres on Saturday.
Also on Saturday, Agen host London Irish and Worcester travel to Pau.