The Irish provinces will be looking for a better return in round two after picking up just a solitary victory on the opening weekend.
Leinster battled past La Rochelle, while Connacht and Ulster fell to demoralising losses, to Bordeaux Begles and Bath respectively.
Munster, meanwhile, were stunned as unfancied Bayonne took a share of the spoils from Thomond Park.
Here's all you need to know ahead of the weekend’s games.
ONLINE
We'll have live blogs, live scoring, reports and reaction across the weekend.
TV
Leinster v Sale is live on RTÉ2 and RTÉ Player on Saturday, with coverage getting under way at 4.45pm. Saracens v Connacht, Ulster v Racing 92 and Exeter v Munster are on TNT.
RADIO
There will be live commentary of Exeter v Munster (kick-off 1pm) on RTÉ Radio 1 Extra and RTÉ Radio on Sunday.
RTÉ Radio 1 will carry updates of Saracens v Connacht and Leinster v Sale Sharks on Saturday. There will be commentary of Leinster v Sale on Newstalk.
WEATHER
London will see sunny intervals on Saturday afternoon in about 11C, while the rain should stay away. Similar conditions are forecast for Dublin and Belfast later in the day with slightly more cloud cover.
Sunny intervals and a gentle breeze in about 12C are forecast for Munster's game in Exeter on Sunday afternoon.
Saturday's games kick off with the meeting of two teams who lost their opening ties last weekend.
However, Connacht’s defeat at the hands of Bordeaux Begles in Galway, and the manner of the 41-5 loss, will have stung much more than Saracens’ 27-16 reverse away to the Bulls.
Pete Wilkins’ side will have to come up with something special to upset the hosts, who have actually lost two of four home games in the Premiership this season.
Billy Vunipola was sent off in South Africa but was subsequently cleared to play in this game.
The Westerners’ last visit to Saracens ended in a 64-6 loss in January 2014.
They welcome back Jack Carty to the starting team, while Owen Farrell starts for the hosts.
Saracens: Alex Goode; Lucio Cinti Luna, Nick Tompkins, Olly Hartley, Sean Maitland; Owen Farrell, Aled Davies; Mako Vunipola, Jamie George, Alec Clarey; Maro Itoje, Theo McFarland; Juan Martin Gonzalez, Andy Christie, Billy Vunipola.
Replacements: Theo Dan, Tom West, Logovi'i Mulipola, Hugh Tizard, Toby Knight, Ivan van Zyl, Tom Parton, Alex Lewington.
Connacht: John Porch; Byron Ralston, Tom Farrell, Bundee Aki, Shayne Bolton; Jack Carty (capt), Caolin Blade; Jordan Duggan, Dave Heffernan, Jack Aunger; Darragh Murray, Gavin Thornbury; Cian Prendergast, Conor Oliver, Paul Boyle.
Replacements: Dylan Tierney-Martin, Denis Buckley, Finlay Bealham, Joe Joyce, Jarrad Butler, Michael McDonald, JJ Hanrahan, Diarmuid Kilgallen.
Referee: Luc Ramos (Fra)
Both Leinster and Sale top their respective domestic leagues ahead of this round two clash at the RDS and both come off the back of victories last weekend.
Leo Cullen's side, in a bid to reach a third successive final, edged a ferocious battle away to champions La Rochelle, 16-9, while Sale had a handsome 28-5 home win over Stade Francais.
Alex Sanderson’s men have lost just twice in the Premiership, while Leinster’s last defeat came on the opening day of the URC season, away to Glasgow.
The hosts name a strong side for the sold-out clash with Josh van der Flier coming in for Will Connors and Ciarán Frawley starting at out-half.
Sale start just three of the side that won last weekend.
Leinster: Hugo Keenan; Jordan Larmour, Garry Ringrose (co-capt), Robbie Henshaw, Jimmy O'Brien; Ciarán Frawley, Jamison Gibson-Park; Andrew Porter, Dan Sheehan, Thomas Clarkson; Jason Jenkins, James Ryan (co-capt); Ryan Baird, Josh van der Flier, Caelan Doris.
Replacements: Rónan Kelleher, Cian Healy, Michael Ala'alatoa, Joe McCarthy, Jack Conan, Ben Murphy, Sam Prendergast, Charlie Ngatai.
Sale: Telusa Veainu; Tom Roebuck, Connor Doherty, Sam Bedlow, Arron Reed; Rob du Preez, Raffi Quirke; Ross Harrison, Tommy Taylor, James Harper; Ben Bamber, Josh Beaumont; Ernst van Rhyn, Sam Dugdale, Rouban Birch.
Replacements: Ethan Caine, Tumy Onasanya, Asher Opoku-Fordjour, Jonny Hill, JL du Preez, Nye Thomas, Tom Curtis, Joe Carpenter.
Referee: Pierre Brousset (Fra)
After two opening-round defeats, Ulster and Racing will be determined to get their European campaigns up and running.
Dan McFarland's men led into the second half away at Bath but faded badly in a 37-14 defeat.
Racing 92, under former Leinster senior coach Stuart Lancaster, lost a ding-dong battle with Harlequins in Paris, 31-28.
Ireland lock Iain Henderson will captain the hosts, while Siya Kolisi and Trevor Nyakane are in the visitors' starting line-up.
Ulster: Mike Lowry; Rob Baloucoune, James Hume, Stuart McCloskey, Jacob Stockdale; Billy Burns, John Cooney; Steven Kitshoff, Rob Herring, Tom O'Toole; Alan O'Connor, Iain Henderson (capt); Dave Ewers, Nick Timoney, Matty Rea.
Replacements: Tom Stewart, Eric O'Sullivan, Marty Moore, Kieran Treadwell, Harry Sheridan, Nathan Doak, Jake Flannery, Stewart Moore.
Racing 92: Max Spring; Henry Arundell, Gael Fickou, Henry Chavancy, Juan Imhoff; Antoine Gibert, Nolann le Garrec; Hassane Kolingar, Janick Tarrit, Trevor Nyakane; Baptiste Chouzenoux, Will Rowlands; Cameron Woki, Siya Kolisi, Wenceslas Lauret.
Replacements: Eddy Ben Arous, Guram Gogichashvili, Gia Kharaishvili, Fabien Sanconnie, Ibrahim Diallo, Maxime Baudonne, Tristan Tedder, Inia Tabuavou.
Referee: Luke Pearce (Eng)
Munster are the last Irish side in action over the weekend and they face an Exeter side who recorded a fine 19-18 come-from-behind victory away at Toulon last weekend.
Sitting sixth in the Premiership, the hosts are unbeaten at Sandy Park this season.
It will be Munster's third visit to a ground where they have drawn one and lost one.
Graham Rowntree said last weekend’s 17-17 draw with Bayonne felt like a defeat so they won’t want to lose any more ground.
Former Leinster players Jack Dunne and Rory O'Loughin are on the Chiefs' bench, while Peter O'Mahony remains out with a shoulder injury.
Exeter: Tom Wyatt; Olly Woodburn, Henry Slade, Joe Hawkins, Ben Hammersley; Harvey Skinner, Tom Cairns; Scott Sio, Dan Frost, Ehren Painter; Rus Tuima, Dafydd Jenkins; Lewis Pearson, Jacques Vermeulen, Greg Fisilau.
Replacements: Max Norey, Nika Abuladze, Marcus Street, Jack Dunne, Ross Vintcent, Stu Townsend, Ollie Devoto, Rory O'Loughlin.
Munster: Shane Daly; Calvin Nash, Antoine Frisch, Alex Nankivell, Seán O'Brien; Jack Crowley, Craig Casey; Jeremy Loughman, Diarmuid Barron, Stephen Archer; Gavin Coombes, Tadhg Beirne (C); Tom Ahern, John Hodnett, Jack O'Donoghue.
Replacements: Eoghan Clarke, Josh Wycherley, Oli Jager, Brian Gleeson, Alex Kendellen, Conor Murray, Rory Scannell, Ben O’Connor.
Referee: Mathieu Raynal (Fra)
FULL LIST OF RESULTS AND FIXTURES
Listen to the RTÉ Rugby podcast on Apple Podcasts, Spotify or wherever you get your podcasts.
