JP was the only player in Scotland's 22-man squad not to get on during last Saturday's historic defeat of England.
But now he is looking forward to what could be a Euro decider at Firhill. JP said in the Daily Record: "It was a massive personal frustration to spend the whole afternoon on the bench.
"Few things are certain in professional sport but one of them is that there will always be letdowns from time to time.
"You have no alternative other than to take them in your stride and not dwell on them.
"I'm the first to agree the Scotland back-row guys put in a fantastic performance and there has been no question of me raising the issue with the coach.
"I'm just thrilled to be getting the opportunity to get back on my horse so quickly for Glasgow and obviously the aim is to put in a strong display."
JP, who was coach Frank Hadden's first-choice as Scotland skipper last year before he suffered a long-term shoulder injury, wants the Warriors to reproduce the form that propelled them to their victory over league leaders Munster last time out.
He said: "Beating Europe's fourth-rated team home and away was a tremendous feat but the problem with our squad is that we have struggled to establish momentum or consistency.
"In terms of booking our place in next season's Heineken Cup, we have to beat the Borders to get our noses in front - then make sure we stay in front.
"Winning at a place like Thomond Park has instilled a great deal of confidence in the team but we must ensure we harness that in the correct way.
"That result, coupled with the Calcutta Cup success, has boosted the feel-good factor in Scottish rugby as a whole.
"The positive vibes have filtered down to every level and we hope this will prompt the fans to turn up at Firhill for a hugely important match."