Make or break for Glasgow
The Warriors welcome the Scarlets to Scotstoun as they look to get their campaign off the ground after a home defeat to Northampton Saints in their only match so-far.
And Townsend reckons their quarter-final charge could be over before it's begun if they suffer defeat against the West Walians on Saturday.
"We would be right up against it if we were to lose this one," Townsend said.
"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.
"The boys have actually been training really well. I don't know if I say that every week, but last week was excellent.
"Today [Wednesday] 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."
The Warriors had an enforced break last weekend after their Scotstoun clash with Leinster was called off.
But Townsend reckons their time off has made his Warriors even hungrier for a Scarlets scalp.
"It's not ideal, but the positive is that players are fresh and even more determined to play a game," he said.
"We also get to train more. 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."
Source: @ChampionsCup