Champions Leicester may not reach the Premiership play-offs
You do not need to be a maths genius to work out that six into four does not go - and the Guinness Premiership is no different.
Gloucester, Wasps, Sale, Harlequins, Bath and Leicester are all chasing one of four play-off spots in the most tightly contested season since the league's inception.
Finishing in the top two will guarantee a home tie in the semi-final play-offs (first plays fourth, second hosts third), and the best chance of progressing to the Premiership final on 31 May.
And if clubs are level on points after the final game of the season, then the team with most wins will finish in the higher position.
All six teams will also want to at least guarantee a place in next season's Heineken Cup, and must finish in the top five to do so.
Of the six places allocated to English teams, the Premiership champions will be one, along with the European Challenge Cup winners, with Bath and Worcester contesting the final on 25 May.
A Bath victory would see the rest of the top six in the Premiership qualify for the Heineken Cup, but a Worcester win would see the side finishing sixth miss out on Europe's elite competition next season.
We assess the prospects for the top six ahead of the final two rounds of the regular season.
Played 20 Points 66 (points difference 164)
Sunday 4 May v Wasps (away)
Saturday 10 May v Bath (home)
The league leaders require one victory to clinch their place in the play-offs, but head coach Dean Ryan will settle for nothing less than a home semi-final, having occupied top spot most of the season.
But there are no guarantees about their last two fixtures - away at Wasps, who have won their last eight, and a potentially explosive West Country derby against fellow play-off chasers Bath.
Played 20 Points 63 (points difference 96)
Saturday 3 May v Saracens (home)
Saturday 10 May v Gloucester (away)
Victory over Saracens, who have little to play for having seen their own Heineken Cup hopes evaporate with semi-final defeat by Munster at the weekend, should be enough for Bath to clinch a play-off place.
But a home semi-final should still be very much on the agenda when they travel to Kingsholm on the final day, and could determine who finishes top of the pile, depending on Wasps.
Played 19 Points 60 (points difference 112)
Sunday 4 May v Gloucester (home)
Wednesday 7 May v Newcastle (away)
Saturday 10 May v Leeds Carnegie (away)
Of all the top six, Wasps have proved past masters at peaking at this time of year, and know that if they extend their current record of eight straight league wins to 11, a home semi-final is guaranteed.
Three games in seven days is challenging to say the least, though if they negotiate Gloucester's visit without further injury problems, trips to Newcastle and relegated Leeds offer succour on the run-in.
Played 20 Points 60 (points difference 50)
Sunday 4 May v Sale (home)
Saturday 10 May v Leicester (away)
Dean Richards' side have been the revelation of the season, and a play-off place would be a significant achievement, but they look the most vulnerable of the current top four.
They face two teams intent on stealing fourth place from them, but beating Sale at The Stoop would galvanise them for a potential winner-takes-all date at Richards' old Welford Road stamping ground.
Played 20 Points 59 (points difference 110)
Sunday 4 May v Harlequins (away)
Saturday 10 May v London Irish (home)
With four victories in their previous five league matches, Sale's resurgence has come in the nick of time, but Sunday's clash with Harlequins provides a stern test of the 2006 champions' credentials.
Defeat there could effectively eliminate them, but victory would be a major step to a play-off place with a home game against London Irish - the only other side that could sneak into the play-offs with a highly unprobable series of results - to finish.
Played 20 Points 58 (points difference 111)
Sunday 4 May v Newcastle (away)
Saturday 10 May v Harlequins (home)
Marcelo Loffreda has endured some uncomfortable speculation over his own position of late, which would only intensify if the champions fail to make the play-offs, having reached the last three finals.
Even two bonus-point victories - against Newcastle at Kingston Park and Quins at Welford Road - may not be enough to make the top four, depending on results elsewhere.