Glasgow Warriors head coach Gregor Townsend knows that defeat to Scarlets would be a massive blow to their Champions Cup hopes this season.
Townsend's men lost out to Northampton in their only match so far of the pool stage, with their opener at Racing 92 having been postponed.
And with back-to-back games away and home against their PRO12 rivals, the Warriors will be desperate for points to kick-start their charge.
"We would be right up against it if we were to lose this one. We have only played one game and there are five to go, we probably have to win four out of five, it would be very difficult if we had to win all the last four," said Townsend, speaking to EPC Rugby's website.
"The boys have actually been training really well. I don't know if I say that every week, but last week was excellent. Today we had 39 players at training. We had guys coming back like Peter Murchie, Glenn Bryce and Fraser Brown, who are now training with the group, which has given us a little bit of a boost. And the whole squad is fresh after the weekend, and you don't often get that on a Monday."
Fixture congestion could well play a major part in Glasgow's season as last week saw their PRO12 clash with Leinster called off due to a waterlogged pitch. However, Townsend believes his players are raring to go after having two games postponed so far this season.
"It's not ideal, but the positive is that players are fresh and even more determined to play a game. We also get to train more," he said.
"Obviously we want to play because this group haven't played that many games since the World Cup, but when this happened two years ago we played Edinburgh on the quarter-finals weekend in Europe and we played Treviso during the Six Nations and did pretty well, so we have experience of this."