The Scarlets trailed 26-0 at half-time to the French giants, and despite Bernard le Roux being sent off early in the second half, the Welsh side couldn't turn things around.
That leaves them well off the pace in the group ahead of a double header against GUINNESS PRO12 champions Glasgow in December.
And Pivac explained that the focus would return to the league and a clash against Zebre before the Scarlets turned their attentions back to Europe.
"It makes it very tough [to qualify] and they'll have to be a lot of turnarounds," said Pivac.
"We came up against a big, heavy pack and it's shown us the standard we've got to aspire to.
"It keeps us grounded, I guess, to see we have a long way to go to get to that standard, and we know that and we've just got to keep working hard.
"We'll see how it goes over the next couple of weeks and we'll see how we go into the Glasgow game looking to get a win."
"We've got to re-focus on the Pro12 and improve against Zebre in a week's time," added Pivac.
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