Leinster must plunder at least a point from fortress Castres
Irish pair have fate in their own hands as going gets tough in pool stages
Pool 1 is the group of death -- the Top 14 champions, Northampton, the Wales/Lions in disguise and Leinster -- the best team in Europe ever.
This was always going to be tight and it seemed almost impossible that one side would be going into round 4 looking as if they had it sewn up. But Leinster were on the march, two away wins in the bag and a home quarter-final was beckoning after three rounds.
Then there was that huge reversal of fortunes against Northampton in Dublin, inspired by the epic Samu Manoa and George North.
Suddenly, everyone is pulling out their abacuses. It was a timely reminder that just one slip in the pool stages in Europe and the rest of the tournament can become knockout rugby very quickly.
Northampton definitely think this group is still alive because Leinster have to travel to Castres this weekend. The Top 14 champions may struggle on the road in Europe, but Stade Pierre Antoine, in the centre of Castres, is their fortress.
They have a hugely powerful pack. Ibrahim Diarra leads the back-row with dogged cussedness, to make up for the absence of Antonie Classenand and, at No 10, they have a proper French fly-half in Remi Tales.
Leinster without Sean O'Brien are a slightly different beast. They still have the pool within their grasp, but this could go any which way. An away losing bonus point at Castres and a win on the final weekend at home to Ospreys will be enough for Leinster. However, should they slip up in France and should Northampton win at Ospreys, then round six will get very twitchy. Despite the fact that Saints are on a roll right now, Leinster are still favourites. They have a simple scenario in front of them; they must get something in France.
Pool 6 looked like anyone's guess midway through the games in round four. Gloucester were just ahead at home to Edinburgh and Perpignan were in control at home to Munster. That would leave Edinburgh gone and the other three in a dogfight with no idea who was favourite for the group.
Gloucester were abysmal in the final 41 minutes at home to Edinburgh. Edinburgh were excellent.
Munster, meanwhile, did what we thought they could not do any more. They believed.
They can still make poor decisions and the quality of their execution is still miles off where it needs to be, but by heck they did not doubt themselves. The instinct of JJ Hanrahan and his fast-stepping feet saw him crash over after dodging four players in the space of a confessional box.
The turnaround now sees Munster head into Round 5 with a five-point lead and yet the unlikeliest of possibilities still remains a chance; Edinburgh, the team in third position, could still win here.
All four sides are still in this because all four sides can beat each other. Munster are not who they were, but are still right in this tournament and have Edinburgh at home in round six. Casey Laulala (left) is still their wild card, but he delivers less than he used to.
I started this group by saying it looked like anyone's guess, but with the doggedness of their back-row and combinations that include O'Mahony, Coughlan, O'Donnell and Dougall, Munster are a lot more comfortable than they were at half-time in Round 4. (©Daily Telegraph, London)
Group winners: Leinster, Toulon, Toulouse, Clermont, Ulster, Munster.
Qualifying as runners-up: Saracens, Leicester.