Holders Wasps were dumped out by Munster on Saturday evening
It was the first time in Heineken Cup history that the competition reached the final round of pool fixtures without a single team having booked a place in the last eight.
BBC Sport gives the lowdown on how a dramatic weekend unfolded.
London Irish W5 D0 L1 Pts 24
Perpignan W5 D0 L1 Pts 22
Dragons W1 D0 L5 Pts 8
Treviso W1 D0 L5 Pts 5
Treviso 11-24 London Irish
Dragons 0-25 Perpignan
London Irish booked their place in the quarter-finals with a bonus-point victory over Treviso in Italy although they did not have it all their own way.
Peter Hewat's try deep in injury time gave the Exiles the five-point maximum that guarantees a home quarter-final.
Perpignan did what they had to do for a last-eight berth, thrashing the Dragons at a sodden Rodney Parade.
Gloucester W5 D0 L1 Pts 24
Ospreys W5 D0 L1 Pts 21
Bourgoin W1 D0 L5 Pts 8
Ulster W1 D0 L5 Pts 5
Bourgoin 21-28 Ospreys
Gloucester 29-21 Ulster
Gloucester made sure of a place in the last eight, and a home tie to boot, with victory over Ulster in an entertaining game at Kingsholm.
The Ospreys did what they had to do in France and their win against Bourgoin - in what could have been a tricky tie - means they are in the quarter-finals for the first time.
Blues W4 D1 L1 Pts 20
St Francais W4 D0 L2 Pts 18
Bristol W3 D0 L3 Pts 12
Harlequins W0 D1 L5 Pts 2
Bristol 0-17 Blues
Harlequins 10-31 Stade Francais
With only one place up for grabs by the time this pool kicked off, the Blues made it all pretty simple with victory over Bristol.
Their 17-0 victory meant they topped the group although they did not do enough to earn a home quarter-final against Toulouse.
Another converted try at the Memorial Stadium would have done it but now they have to settle for a trip to France.
Stade Francais kept their side of the bargain by beating Harlequins with a bonus point but with the Blues winning, it was all in vain.
Saracens W5 D0 L1 Pts 24
Biarritz W4 D0 L2 Pts 18
Glasgow W3 D0 L3 Pts 16
Viadana W0 D0 L6 Pts 3
Biarritz 25-16 Viadana
Glasgow 17-21 Saracens
Saracens guaranteed themselves a home quarter-final with a 21-17 win away to Glasgow on Friday night.
The result meant they finished on 24 points and will be one of the top four seeds come the knock-out stages.
In the other Friday night encounter Basque aristocrats Biarritz won 25-16 at home to Italian side Viadana to claim second place in the group.
However, the result is unlikely to be enough for them to go through as one of the two best runners-up in the six pools.
Munster W4 D0 L2 Pts 19
Clermont W4 D0 L2 Pts 19
Wasps W4 D0 L2 Pts 18
Scarlets W0 D0 L6 Pts 0
Munster 19-3 Wasps
Scarlets 0-41 Clermont
From heading the group at the start of weekend, reigning champions Wasps slipped to third and out of the competition after their loss to Munster at Thomond Park.
Munster's 19-3 victory moved them up to first, and a place in the quarter-finals, while Clermont finished in second after their thumping of the Scarlets.
The French-side's bonus-point win could be enough for a place in the last eight but they are now dependant on Sunday's results.
Toulouse W4 D0 L2 Pts 20
Leicester W3 D0 L3 Pts 14
Leinster W3 D0 L3 Pts 12
Edinburgh W2 D0 L4 Pts 9
Leicester 25-9 Leinster
Toulouse 34-10 Edinburgh
Leicester were out of the running after their defeat in Scotland last week but denied Leinster a chance at the last eight in a bruising clash at Welford.
Three-time champions Toulouse beat Edinburgh comfortably at home to set their sights on a fourth title.