The top two teams in all six pools play each other twice before Christmas. But it could lead to dead games in January

Perfect symmetry is rare in rugby union. Not this week. The middle fortnight of the Heineken Cup pool stages is always significant but the tournament is about to witness something unique. By a quirk of fate, the top two teams in all six pools will be playing each other home and away in rounds three and four. It is more than possible a number of pools will be virtually settled by Christmas.

This is unusual to say the least. Traditionally, supporters are still sweating on pool winners entering the final minute of the final games in January. This time around six clubs – Scarlets or Munster, Edinburgh or Cardiff Blues, Leinster or Bath, Leicester or Clermont Auvergne, Saracens or Ospreys, and Toulouse or Harlequins – could secure near-certain quarter-final qualification way ahead of schedule if they achieve successive wins this weekend and next.

It clearly remains a big "if". The beauty of Europe is that beating Toulouse, say, on a Friday night in south-west London is absolutely no guarantee of doing likewise on the banks of the river Garonne the following week. Last season six teams out of 24 managed to achieve a home-and-away double at this stage of the competition. The previous year it was seven. Would you bet on Bath beating Leinster home and away inside seven days? Thought not.

In the short term it adds lustre to an already fascinating period of the season. If there is an outstanding team or two in this year's tournament, we are about to find out earlier than normal.

Should Quins, unbeaten in 14 games in all competitions, defeat Toulouse twice in a row they really will deserve universal respect. Ditto the Scarlets, so impressive in Northampton, against Munster. No Welsh region has yet lost a game in Europe this season. If that record is still standing in a fortnight's time, it will hardly be a fluke.

The way the round three and four fixtures have fallen, even so, is not necessarily ideal. Let us say the six current pool leaders – Scarlets, Edinburgh, Leinster, Leicester, Saracens and Toulouse – all bag a brace of victories. Even if none of them score a bonus point, it will leave them knowing precisely what they have to do in their final two January games. The scramble for the last two qualifying places and home draws in the quarter-finals would still be intense but the number of dead games would potentially increase.

This matters because the tournament's season-long appeal is built on every match contributing significantly to the bigger picture. If a side are down and out by Christmas, they may well be tempted to stick out a weakened side in January, upsetting the balance of the entire competition. This year's pool draw has already been subtly smoothed by the seeding of sides based on their record in the Heineken Cup over the previous four years.

Others still wonder about the structure of the tournament – currently confirmed until 2014 – of three blocks of pool fixtures. It continues to mystify new arrivals to Europe, who are used to the Super 15 being played to a finish without other competitions interrupting it. One day, you suspect, someone will suggest starting the Heineken Cup in late March, after the domestic leagues and the Six Nations have been completed, with a final in late May/early June. The frequently poor weather that threatens European ties across the continent in December and January is one more reason to consider such a proposal.

For the next fortnight, though, such debates can wait. Apart from Leinster at Bath, it is hard to see too many away wins in the six pivotal "top of the pool" Heineken fixtures this weekend. That would certainly help prolong the suspense but, ultimately, the tournament will be judged on the number of quality matches played between now and May. This season is already promising in that regard, regardless of how many runaway pool winners there are. A sting in the tale surely awaits at some stage.

Big boots to fill

The retirement of Steve Thompson removes another larger-than-life character from the England rugby scene. Thommo will be much missed by fellow players, fans and journos alike; to have fought his way back from his previous retirement, after which his weight had ballooned to 21 and a half stone, to play in another World Cup for his country was an extraordinary achievement. He joins the equally valiant Joe Worsley in hanging up his boots, leaving only four of England's 2003 World Cup final squad still playing professionally. Lewis Moody, Mike Tindall, Jonny Wilkinson and Iain Balshaw are still soldiering on but for how much longer?

Worth watching this weekend

Ronan O'Gara (Munster). Having clinched his team's first two games with last-gasp drop goals, the steely Irish stand-off is due to make his 100th Heineken Cup appearance against Scarlets this weekend. So far he has amassed 1,221 tournament points and has scored in his past 82 Heineken Cup appearances. "He knows just what he has to do and when to do it," stressed his familiar Welsh adversary Stephen Jones. A third successive late drop-goal winner would be too much to ask for, wouldn't it?