This season's Champions Cup is less than two weeks old, but already there are a number of crucial fixtures taking place across round two.
Buoyed by their late show against Montpellier, Northampton Saints travel to Castres knowing victory is likely to end the Top 14 side's hopes of reaching the knockout stages, and the same applies for Northampton's Pool 4 rivals Leinster in Montpellier
Defending champions Saracens are up against a Scarlets side that have found some form after a sticky start to the season, while Bordeaux-Begles could again scupper Clermont Auvergne's quarter-final hopes if they win at the Stade Marcel Michelin for the second successive season.
Farewell to a legend
Emotions will run high for the first European meeting between the PRO12 heavyweights as Munster supporters pay tribute to Anthony Foley.
The Munster players and coaching staff have taken the brave decision to go ahead with their Champions Cup fixture against Glasgow and it is fitting that the first game after Foley's death is at the stadium and tournament he graced with such distinction.
"One's life is greater than any sport or sporting occasion, however Thomond Park held a special place in Axel's heart," said Munster director of rugby Rassie Erasmus.
"As difficult as it will be to play the next game, no matter the time, opposition and venue, we have an opportunity to play there this Saturday; that is something that is hugely important to all of us and cannot be easily dismissed.
"Playing in Thomond Park further ties us to his memory and will be a chance for all, including our supporters and the community, to feel that connection and closeness to him at this time."
Books of condolence will be open for supporters at Thomond Park from 11am on Saturday. A minute's silence will be observed prior to kick-off with a special tribute taking place in the West Stand, while the Munster Supporter's Club Choir will perform 'There is an Isle' and soprano Sinead O'Brien will join the choir to sing 'Stand Up and Fight'.
Can Saints win in France?
Northampton got out of jail last week when Stephen Myler's last-gasp penalty snatched victory against Montpellier and they must try to buck their poor record across the Channel when they visit the Stade Pierre-Antoine.
Saints have lost their last six away games in France, and their last three in Castres. But this is a good time to be facing Christophe Urios' side, who have lost three games in a row and were dominated up front against Leinster.
Like all French teams, Castres will be more of a force on home soil and they have scored 10 tries in their last two home games, which includes a win over Top 14 champions Racing 92. That is in stark contrast to Saints, who have managed just 11 tries in seven games this season and are yet to settle on a centre combination.
The return of Dylan Hartley is a major boost for Jim Mallinder's men - although Mike Haywood was rock-solid against Montpellier - and Louis Picamoles will be out to impress on his return to France.
The last time Northampton won back-to-back games against Top 14 opposition was in the 2010/11 pool stages, when they beat Castres home and away. If they can repeat the trick on Saturday it sets them up nicely for their December double-header with Leinster.
Another cracker in Clermont?
These sides produced a thrilling conclusion to last season's pool stages when Bordeaux registered a stunning win at the Stade Marcel-Michelin and had everyone reaching for their calculators.
The 37-28 defeat was Clermont's first European loss at home since 2008 and Morgan Parra's late moment of madness, when he tapped a penalty in front of the posts when three points would have earned them a losing bonus point, cost them a place in the quarter-finals.
Clermont have started this season on fire, losing just one of their opening nine games, and they tore Exeter apart last weekend with the likes of Wesley Fofana, Nick Abendanon and Julien Bardy in scintillating form.
But Bordeaux are also motoring nicely and they travel to the Auvergne looking to extend their four-game winning streak. They finished strongly to see off Ulster last Sunday and another win in Clermont would put them on course for the quarter-finals for the first time.
Can anyone stop Saracens?
The Scarlets started their Champions Cup campaign in style with victory over Sale but they face the toughest challenge in European club rugby on Saturday when they attempt to beat Saracens on their own patch.
Sarries started their title defence in stunning fashion as they ended Toulon's unbeaten European record at the Stade Felix Mayol, even denying the hosts a losing bonus point.
And Saracens have been just as impressive at Allianz Park, where they have won their last nine Champions Cup fixtures.
Mark McCall's men are capable of playing a variety of different styles and already look an improved version of last season's double-winning side. They remain as ferocious and unrelenting as ever in defence but look more threatening in attack, their handling and offloading skills in particular catching the eye in Toulon.
Scarlets have game-breakers in Wales duo Gareth Davies and Scott Williams and they will need to be at their best in north London to unlock a defence that has conceded six tries in seven outings.
Wales' sole Champions Cup representative are seeking back-to-back wins in the competition for the first time since 2011. It would rank as one of the best results in their history if they emerge victorious from their first European meeting with Saracens.
Sexton and O'Brien back for Leinster
Good news for Leinster as they welcome back Johnny Sexton and Sean O'Brien, two big-game players for the Irish province. In Sexton's absence, Joey Carbery has made an incredible start to his Leinster career and thrilled on his European debut against Castres. However, Sexton has recovered from his hamstring injury and his experience will be needed against Montpellier.
It's a big ask. Montpellier have scored 11 tries in their last three home fixtures and will be smarting after last weekend's last-gasp loss in Northampton. Had Nic White managed to find touch - and Francois Steyn not been reprimanded by Nigel Owens - last year's Challenge Cup winners would be in pole position to qualify from Pool 4.
Montpellier's pack will provided a much sterner challenge compared to Castres, but the return of flanker O'Brien will certainly give them another big ball carrying option and release the likes of Garry Ringrose and Robbie Henshaw out wide.