They are in a position to do so this weekend during the climactic weekend of the pool competition when it pays to have a degree in applied mathematics and nerves of steel.
Once the calculations are all done and dusted, the number five might just be more important than any other when it comes to counting how many from the RaboDirect PRO12 have made it into the quarter-finals of the Heineken Cup.
Holders Leinster are already there, unbeaten now in eleven European matches as befitting their champion status.
Munster, still the only one of the 24 starters to win all their pool matches hitherto, are with them and it says everything about the ferocity of the competition that they cannot yet be certain of a home quarter.
Only by preserving their 100 per cent record when they break new ground against Northampton on Saturday and the Red Army occupies the MK Dons' football stadium will Munster be sure of returning to Limerick when the tournament resumes in April.
A losing bonus point may well be enough - not that the Celtic champions have got where they are by entertaining the thought of losing anything.
Cardiff Blues, Edinburgh and the team of the weekend, Ulster, are poised to join them in the charge from the RaboDirect Pro 12 towards the top eight in Europe.
By contrast, the Aviva Premiership could be down to one qualifier, Saracens, after a weekend when Ulster's tour de force against Leicester left the bleeding Tigers nowhere to go other than out.
A home double over Racing Metro on Sunday will take the Blues through but they may need the try-bonus to be sure of preventing Edinburgh from winning the pool in a photo-finish at Murrayfield during their simultaneous match against London Irish.
No sooner had Phil Godman done a Ronan O'Gara and dropped the winner against Racing with the last kick in Paris last Friday than the Scots began drumming up support for this Sunday's finale.
The drop keeps Edinburgh flat out for their first quarter-final in eight years which, by coincidence, happened to be when Godman went back to the Scottish capital.
He did so on the basis that a return home offered a better future than remaining on Tyneside and trying to shift Jonny Wilkinson at Newcastle.
The rallying calls for a crowd similar to their RaboDirect record of more than 13,000 against Glasgow on Boxing Day will leave no doubt that the Scots have something to shout about.
Godman, who made the last of 16 starts for Scotland two years ago, underlines the point.
"If ever there was a time to come and try out a game of professional rugby, or introduce a friend to Edinburgh rugby, it's this coming Sunday," he says in pleading for the support to ensure Scotland are represented in the last eight for only the second time since the competition began 17 years ago.
In the event of Cardiff and Edinburgh finishing as they are now, level on points, the Welsh Blues will win the pool by virtue of the aggregate score of their two matches against Edinburgh: 37-27, even though the Scots outscored them 2-1 on tries.
Every outcome remains possible for both teams, from qualification to elimination, which ought to guarantee a Sunday of rare tension in the Welsh and Scottish capitals.
Saturday in the Massif Central will be hard to beat in terms of white-knuckle anxiety. The Clermont Auvergne-Ulster is a winner-take-all decider, a case of the immovable object meeting the irresistible force.
The Michelin Men have been immovable at home to such an extent that they have won 36 consecutive matches there since November 2009 when Biarritz beat them in the Top 14.
Ulster, irresistible in destroying Leicester as they have never been destroyed before, will aim to reproduce the same fury on Saturday afternoon and see how Clermont's cosmopolitan crew cope with the oxyacetylene treatment.
Leicester, beaten 30-12 at Clermont before Christmas, found the heat at Ravenhill unbearable.
The Tigers had suffered there before, of course, on a Siberian Sunday lunch-time in January 2004 when they were still the team to beat in Europe. Martin Johnson came off the bench that day but failed to stop the rot which added up to a 33-0 beating.
At least then, Leicester then could do something about it which they did in the return match the following week, winning it 49-7.
Without any chance of a reprieve, they are now reduced to playing out the one remaining fixture, Aironi at Welford Road knowing that no amount of tries will make a blind bit of difference to their fate but for a mathematical miracle.
The door to the consolation of a drop down into the Amlin Cup had also been shut before Paul Marshall's bonus try allowed Ulster to go one point better than eight years ago as due reward for their all-round brilliance.
Despite what must have felt like the worst night of his professional rugby life as a Leicester player and their director of rugby, Richard Cockerill deserves praise for reminding everyone that the game has not lost its old-fashioned virtue of being gracious in defeat.
"You have to take your hat off them, shake their hands and say: 'Well done,'" Cockerill said. "They played very well."
He could always have moaned about the referee, as many a football manager might, but that would not have been Cockerill's style.
He showed the same generosity of spirit in similarly dire circumstances in Swansea two years ago after the Ospreys had knocked Leicester out, refusing to exploit the hoo-ha over the 16th man row swirling around Lee Byrne's unauthorised return to the field.
Cockerill knows a beating when he sees one and Leicester hadn't taken one as big anywhere in Europe as they took at Ravenhill on Friday night.
At least eight of those responsible - six native Ulstermen and two Springboks - demanded selection in any composite best European XV of the weekend: Andrew Trimble, Darren Cave, Craig Gilroy, Ruan Pienaar, John Afoa, Rory Best, Stephen Ferris and Pedrie Wannenburg.
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