Leinster coach Michael Cheika believes his side's trip to Twickenham Stadium to meet London Wasps in Round 5 is going to be "a straight shoot-out" for the Pool 2 title.
Having seen his side throw away a golden chance to consolidate their position at the top of the Pool with an 18-15 defeat to Castres Olympique in France, Cheika said it would be back to the drawing board over the Christmas period.
"We let an opportunity slip to be in charge of this Pool. We have to get better," said Cheika.
"Unless we get better, and more solid in the pressure moments, we won't go any further in the competition even if we get out of the Pool. Every game is so important.
"We didn't play well and we got beaten. It is a shame it has ended up that way after such a good start.
"We can't afford to have another loss after this. It is a straight final almost against London Wasps.
"We have got to get our game back to the level it was in the first two rounds. That's going to be a process we will have to be hard with.
"We have to make sure that by the time we get to the Wasps game we are in good shape."
The directors of ERC voted unanimously at a Board meeting to postpone all decisions including the release of further instalments of ERC's distributable central revenues to the six shareholder countries until 19 February next when the Board will meet again to reconsider the issue.