Wales captain Sam Warburton accepts that Cardiff Blues will probably not know their Heineken Cup fate until after the final whistle sounds on Sunday's Pool Two programme.
The Blues host already-eliminated Parisians Racing Metro, while Edinburgh entertain London Irish with Cardiff and their Scottish rivals currently tied on 17 points. Warburton and company could be out of the competition by Sunday evening, celebrating a Heineken quarter-final spot or even finding themselves in the second-tier Amlin Challenge Cup knockout phase.
"It's going to be a funny one in that we will have to give it our all, but we perhaps won't know until the final whistle if it is good enough or not," Blues flanker Warburton said. "All we can do is focus on ourselves and do everything we can to make sure we get that win."
He added: "Normally, teams would think they could well be in the quarter-finals with four wins at this stage, but it has been a tough group and Edinburgh are pushing us all the way.
"I don't think a lot of people expected this scenario, especially Racing having three home defeats.
"It is very tough to go to France and win, but that has opened the group right up and Edinburgh will throw everything at Irish, so it is going to be a really close one to call.
"Getting a home semi-final is a huge incentive. If we could get five wins I think we probably would be one of the top four qualifiers, and a home quarter-final draw would be fantastic.
"I was up in the stand for that semi-final in 2009 when more than 44,000 turned up for that Leicester game at the Millennium Stadium.
"That is the sort of game in which you want to be involved, and in the last two years we haven't quite been there. You really want to win the big one, and that is the Heineken Cup."
The Blues are again without Wales centre Jamie Roberts, who is recovering from a knee injury, while Gavin Henson has been replaced by Gavin Evans alongside Casey Laulala in midfield.