The penultimate round of fixtures in the Champions Cup pools gets underway this weekend, with some huge team selection calls being made.
It is make or break for sides aiming to progress in the top two places to get a home draw in the next round.
Others who have not started their European campaigns well face a fight to stay in the competition and must bring their A-game.
Antoine Dupont makes his first ever southern hemisphere start and Rob du Preez faces a stern test on his return to home country South Africa.
Here are the best match-ups to look out for in a crucial period for plenty of teams.
Racing 92 head to Glasgow to face the Warriors in a crucial game for the Paris side. Having won one and lost one with no bonus point, failure to win would effectively resign them to either Challenge Cup or out of continental rugby completely.
It is a stronger but still not completely full strength team in Scotland and the experience of 36-year-old Henry Chavancy will be crucial at centre.
Scotland international Sione Tuipulotu is his opposite number, who has more international caps than the Racing player.
An interesting battle between two leaders and two players who are both extremely intelligent, the winner in midfield could well decide the winning team.
Sale Sharks’ Rob du Preez still has a lot to prove in his native South Africa, with the versatile fly-half returning to face former side Stormers.
He seems to have never been truly appreciated in his homeland, having only one international cap to his name for the Springboks.
After a few successful games at centre, he returns to fly-half with Boks regular Manie Libbok starting for Stormers.
Should RDP outplay his direct opponent, people in his native country may finally give him credit and recognise him as a top-level player.
It won’t be easy, with Libbok being such a good playmaker, but du Preez’s kicking could see him have a huge say on this game.
Antoine Dupont makes his second ever appearance and first ever start in the southern hemisphere when Toulouse play Sharks in Durban.
As one of the best players in the world, the France international must play well to silence the doubters, who think that his lack of global experience means that he cannot be considered in the top bracket.
Jaden Hendrikse is an upcoming Springboks star and the perfect opponent for Dupont to show his class against.
The powerful carries at the gainline from Jaden may prove too attritional for his opponent to handle in the hot and humid conditions.
It will be a battle between two big locks with an identical surname when Ulster travel across the Irish Sea to play against Leicester Tigers at Welford Road.
Both are at opposite ends of their career, with Iain in his 30s now and Cameron still at the youthful age of 24.
Having twice been on the British and Irish Lions tour, Ireland international Iain must make sure he isn’t outplayed by the new kid on the block.
Six foot seven Cameron is yet to get a properly consistent run of games and European performances are a perfect way to start that off.
Two internationals battle it out at number eight in Toulon’s clash with Harlequins on Sunday.
Quins could leapfrog Toulon and go top of the pool should they win, and other results go their way.
Both are some of the best in their position and are strong runners and tacklers, with the intelligence that is required too.
While it is not seen as the most glamourous position, it makes the team tick and provides an important platform for everyone else to play well from.
Marcus Smith signing a new, number contract at Quins shows just how much he is rated there as a fly-half.
Paolo Garbisi may not be a household name like Smith, but is a very capable player and an international for Italy.
Should Toulon wish to stay top, they will have to fight off a strong challenge from their Premiership opponents, who have put out a strong side.
Marcus is cited as one of the best kickers in the game, which will prove to be an important attribute to relieve pressure and score points at crucial times in what will be a huge game in the south of France.
Clermont and Bath are both playing with a lock who has been at the club for over ten years.
Former Fiji international Peceli Yato has been a mainstay at Clermont since his 2014 arrival, with Charlie Ewels playing for Bath for the same amount of time.
Ewels had a brief loan hiatus to the Blue Bulls in the Currie Cup and is now one of the most important players for the current Premiership leaders.
As captain, the England international needs to regain favour for his country, having fallen out of Steve Borthwick’s plans recently.
Leading his club side to European glory would be a perfect way to prove himself, but after two losses from two a win is essential to try and see his team through.
READ MORE: Antoine Dupont set to make second southern hemisphere appearance when Toulouse face Sharks