With just two rounds of European group stage action remaining this term, the Heineken Cup is reaching fever pitch.
Only the continent's best and brightest will succeed in making it through to the competition's quarter-finals, with one of rugby's most prestigious awards on the line.
Although some have bowed out early thanks to a lack of initiative in the tournament, a raft of teams remain in the running to progress, the problem being that only eight places are up for grabs.
Ahead of Matchday 5, we run through the remaining fixtures, examining which clubs are most likely to continue their 2013-14 Heineken Cup journey, with 16 other teams bowing out of the running as a result.
Matters are tight at the to of Pool 1 where three-time Heineken Cup champions Leinster have done well to take early advantages over fellow European hopefuls Northampton Saints and Castres.
The Irish marauders are currently four points clear at the top of their group, and this weekend's trip to southern France promises to have a grand impact on Matt O'Connor's hopes of leading his side through.
Castres have been a difficult team to score points against when playing on their own turf this season, but the boys in blue showed back at the RDS almost three months ago that they've got the means of beating the Top 14 outfit.
Providing that fixture is won, it should be a fairly simple canter to the quarters, with a matchup opposite bottom side Ospreys awaiting on Jan. 17.
Leinster's loss at home to the Saints was a setback that promises to give the Premiership club a much-needed peek at coming out on top of the group, but a win this week would essentially seal the deal for Leinster and a bonus point possibly up for grabs on Matchday 6.
Everybody loves an underdog story, but there won't be any such like for Pool 2's Cardiff Blues this season.
Instead, the European contenders will be forced to watch a Toulon cast packed to the rafters with star talent qualify for the tournament's upcoming phases.
As things stand, the pair are just two points apart, the reigning Heineken Cup champions on 15 while the Blues sit with 13 to their name, Exeter Chiefs following in a distant third on just seven points.
With that being the case, this weekend's meeting at the Allianz Riviera will essentially make or break Phil Davies' hopes of guiding his side forward, another four points good enough to seal qualification for Toulon.
And that will be precisely the course of action for the French hosts, who have so far claimed a bonus point in each of their home games in this Heineken Cup campaign. They will be going up against a Blues team recently rocked by the long-term injury suffered by budding superstar Rhys Patchell.
Undoubtedly one of, if not the most difficult group winner to predict at the moment, Saracens sit level on points with Toulouse in Pool 3, with each team claiming 15 points from their first four European outings this campaign.
Again, this weekend's fixture at the Stade Ernest-Wallon is therefore likely to decide who goes through as the pick of the bunch.
Toulouse have looked shaky at times in recent weeks. Guy Noves' side are coming off the back of a triumph over Clermont Auvergne, but they've managed to score just 64 points in their last four league home matches.
The likes of Bordeaux, Toulon and even Oyannax have all been able to restrain the French giants in their own respects, regardless of where the match is being played.
Meanwhile, Sarries have been rampant in all regards and the club currently leading the Aviva Premiership are unlikely to be fazed by the prestige that Toulouse have at their disposal, boasting more than a little of their own.
This particular clash of the titans will be one of the most tantalising fixtures of this season's group stage, the packs and back lines on display each being of a superstar standard.
It's highly likely that each club will claim a minimum of four points on Matchday 6, Saracens hosting Connacht while Toulouse travel to Zebre, so the upcoming encounter between the two will decide all, the English representatives benefiting most.
Having made the final last season, Clermont's have once again taken a controlling grip on matters in Pool 4 and currently boast a four-point advantage over Harlequins.
The pair currently have 15 and 11 points respectively, with Scarlets and Racing Metro as good as out of the running, claiming six points apiece with just two matches remaining.
As do numerous pool leaders, Clermont face possibly their most difficult challenge of the group phase this weekend, where they'll travel to the Stoop with a view to stretching the distance between themselves and Conor O'Shea's men.
It's far from an impossible task given that Vern Cotter's outfit triumphed 23-16 in the reverse fixture, that bonus-point loss just about keeping Quins' hopes of coming out on top of the group alive.
However, Harlequins already showed in their Matchday 1 loss at home to Scarlets that they can be exposed should things not go according to plan and Clermont will be a test of totally different proportions.
It was only six weeks ago that the Vulcans managed a dominant demolition of Racing Metro in the Top 14, so a Matchday 5 win on English shores will set up the foundations for a repeated feat the week after, Quins helpless but to settle for a runners-up spot.
Challenging Toulouse and Saracens for the title of toughest pool winner to predict comes Leicester Tigers and Ulster, three points apart and with an almighty encounter scheduled for Jan. 18.
Before that, however, the Irish powers must validate their billing as suitable candidates to qualify automatically, hosting a tricky Montpellier side this weekend while the Tigers have a fairly rudimentary run out scheduled against Treviso.
Mark Anscombe's side will be on a high after winning against Munster over the New Year's Pro12 period, but the visit of the Top 14 titans threatens to derail their Heineken Cup bid.
In all likelihood, Richard Cockerill's side will once again claim a bonus point win over their Italian hosts for the second time in succession, but Ulster could very well slip off the pace at Ravenhill.
Regardless, matters will rest on the direct clash between Leicester and Ulster the following weekend, where the English giants have a chance to seal the deal and make the best of what's been a disappointing campaign domestically.
Coping with injuries and the news of Toby Flood's summer departure to Toulouse, per BBC Sport, Leicester will receive a boost thanks to a somewhat surprising win over Anscombe's outfit next weekend.
As long as the Tigers beat Treviso, the worst-case scenario is that they'll be four points behind Ulster come Matchday 6, but it would be highly surprising to see the province claim a bonus-point win over Montpellier this term and an impending loss at Welford Road.
Munster have been far from fantastic in their Heineken Cup trials so far this campaign but have benefited from being slotted into a relatively weak group.
It's likely that the quarter-finals will give Rob Penney's men a sterner test of their mettle, but until then a place in the final eight is theirs for the taking.
On 14 points, Gloucester are the Red Army's closest competitors five points behind, while Edinburgh and Perpignan have eight and seven points, respectively.
With Penney having recently seen his side claim back-to-back wins over Pool 6's French representatives, it's time for the rule to be run over the remaining two.
Kingsholm has borne great fruit for a number of English sides in this Premiership season, making this weekend's trip to the Cherry and Whites a promising one for Munster, Edinburgh and Perpignan having scored a collective 38 points at the ground this season.
Considering four points should go in the direction of the visitors on Matchday 5, it's then only a case of seeing out a visit of the group's second-weakest attacking side, Edinburgh.
In truth, these fixtures may yet prove difficult for a Munster side that has shown its holes of late, most recently against a resurgent Ulster line-up, but the European titans will have the necessary depth to go undefeated in their remaining outings.
Since bonus points were introduced in the 2003-04 season, no side has ever qualified for the Heineken Cup quarter-finals as highest-scoring runner-up with less than 19 points.
Considering Toulouse and Ulster already have 15 and 18 points respectively, and two fixtures remain in the pool stage, their chances of maintaining that record would certainly look strong.
The other two high-scoring pools looking to threaten the aforementioned pair would be Pools 2 and 4, where Cardiff Blues and Harlequins sit relatively comfortably on 13 and 11 points respectively, but will ultimately fall out of favour as a result of their opening four matchdays.
As mentioned earlier, Noves' Toulouse still have a superb chance of qualifying at the head of their group considering they sit level on points with Saracens, but a climactic pool stage finisher against Zebre offers the French squad the chance to take their tally to 19 at the very least.
Ulster are arguably even better off with their tournament high of 18 but face a difficult run-in against Montpellier and Leicester.
That being said, a winner in either of those matches will be good enough to ensure them of a spot in the quarters and that's not too tall an order for Anscombe's impressively deep line-up.