Irish heavyweights Leinster could see their two-season reign as European champions come to a grinding halt this weekend.
A bonus-point victory against Exeter at Sandy Park is the requirement for Brian O'Driscoll and company on Saturday night, but it still might not be enough.
Leinster can only clinch one of two best runners-up spots available in the quarter-finals, and with Munster and Montpellier among other teams also hotly contesting those places, a pool-stage exit cannot be ruled out.
Tournament favourites Clermont Auvergne, who visit the Scarlets on Saturday, have already won Pool Five and Exeter now stand between Leinster and possible progress.
"It would be a fantastic achievement if we could finish with a win, primarily because of the pressure Leinster are under to come here and win and chase a bonus point," Chiefs head coach Rob Baxter said.
"They will be coming here full-on, which is good for us, and the kind of scenario we want to play in. I don't want us to be playing in a dead rubber of a game because you don't learn too much from those types of games.
"What we need to do is learn to cope with the intensity, like that of last week in Clermont."
The Scarlets welcome back fit-again Wales wing George North against Clermont, with the visitors parading a trademark galaxy of international talent such as Lee Byrne, Aurelien Rougerie, Morgan Parra and Julien Bonnaire.
Ulster have already wrapped up Pool Four, but a bonus triumph in Castres guarantees them a home quarter-final, with Northampton knowing they need a five-point maximum away to Glasgow in their slim quest of progressing beyond the pool stage.
Sale Sharks conclude their European campaign away to Cardiff Blues, with both teams having failed dismally to make any impression on a group dominated by Toulon and Montpellier.