So what happens if we lose this match. Toulouse cannot be taken for granted and their away form is as frightening as their home form.
Leinster are only two points behind our pool rivals, however, if we lose tomorrow it is the other pools that will decide whether we progress or face a long hard disappointing year, thinking of what could have been.
We will know by kick-off whether Munster have won away to Gloucester, putting them ahead of us on points if they do. A home game against Exeter next Saturday would still not guarantee them a home quarter final, but it would remove the Chiefs from the running for best runner-up.
Unfortunately, this might open the door to Castres to clinch it. Their game against Exeter this Sunday will either make for a thrilling showdown next week or allow Leo Cullen and company to sleep better this coming week.
If the Chiefs win, we can hope that Munster will beat them next Saturday at home, and keep them from rising above us. We will still need to win against Wasps, but the margin will be bigger.
Only three out of the five runner-up teams will progress to the next round. What other groups could take one of those bottom placed spots?
In pool 3, we can expect Saracens to beat Lyon on Sunday, but what about Glasgow against Cardiff? Derby games, or regularly run ones, sometimes throw up strange results. Still, it is probably too much to expect the Welsh province to get a result away from home. Expect Glasgow to move up to at least eighteen points by the weekend.
Next week, however, is a different story. They will play Saracens away from home. Even at their best, this would be a difficult ask. Let’s give them a possible twenty points at the end of it. That makes for tight margins. If Leinster lose and don’t secure the bonus point in defeat tomorrow and next week against Wasps, we could be in trouble.
Pool 4 sees our rivals up the M1, Ulster host Racing 92, who are one of the form teams again this year. They have yet to prove to me that they can win in Europe when it counts, but they come knowing that a win in Belfast will likely secure them a home quarter final.
Ulster are away to Leicester Tigers next week, who have shown terrible form in all competitions this year. Let’s give Ulster twenty-two points but still only finishing in second spot. If Leinster lose, they will finish ahead of us.
The last group is more promising with three teams in the hunt. Toulon are out of the competition, surprisingly, but Edinburgh face a tough trip there to move out of touch from Montpelier in second, and the Newcastle Falcons in third.
Montpelier are at home to the Falcons, and the French side should secure the win. That game takes place simultaneously with Leinster’s fixture. If the Falcons can pull off a result, as they did against Toulon in round two, then that would be good news for Leinster.
So it is more likely that Montpelier will travel to Edinburgh next Friday night to try to clinch second place and a spot in the quarter finals. They may finish on twenty-one points, but nineteen is the more likely tally.
Either way it is going to be close. Lose tomorrow and we face an extremely nervous weekend and week, watching other games, feverishly doing the maths, and then re-doing it as the results change.
A win is will not mean qualification, at least not until we see the results of the other games, but it will add a certain amount of comfort. We will still need a result next week, but it means we can be looking at winning to stay at home in the quarter finals compared to winning and still missing out.
We play on Sunday next week. The final game of the pool stages. We will know exactly what we need. We will know if the result will be futile. Everything rests on the game tomorrow.