Jason Forster and his Newport Gwent Dragons are now the only Welsh hope of qualifying for the quarter-finals - but their destiny is not in their own hands.
Newcastle Falcons, who lost their 100 per cent record in Perpignan on Saturday, will qualify as Pool 5 winners with a victory over the Dragons at Kingston Park.
No ifs or buts there but the Dragons and Perpignan, who travel to the Scottish capital to meet Edinburgh Rugby, are level on 15 points after Round 5 and if they both picked up the same four or five point wins, Perpignan will go through with the superior head-to-head record against the Dragons. Both sides have five match points from their two-leg series, but Perpignan lead 6-4 on try-count.
"We are in with a shout - along with Newcastle and Perpignan - of progressing to the quarter-finals and all three of us know that we have to win our final matches to have any chance," said Dragons team manager Jim McCreedy.
"However, Newcastle are in the driving seat. If they beat us, that is that - they win the Pool and are in the quarter-finals."
Newcastle won 10-6 at Rodney Parade in Round 1 and Jonny Wilkinson's latest injury suffered on Saturday means he will have missed both matches against the Dragons.
"Newcastle are a quality side and Jonny didn't play in Round 1 either so we know the task ahead for us," said McCreedy.
"However, we have got some momentum going at the moment and we will be out to maintain that in Newcastle. Our performance against Edinburgh was full of confidence and we scored some excellent tries."