Among the replacements are Stuart Hogg, Scotland's outstanding back of last season, and Jonny Gray, younger brother of Richie, who has been the national team's best forward for the past year.
Both were surprises, for very different reasons, but the reasoning was similar with Townsend explaining that the way they have been playing explains Hogg's absence from the starting line-up and 18-year-old Gray's introduction to the squad.
"There's a lot of competition in that back line," he said of Hogg. "In the back three, Peter Murchie's been one of our best players this year and Stuart hasn't been in the best form, but I'm hoping he will have a big part to play in the two games. It shows the competition we have in that back line that someone like Stuart is on the bench."
As for the suggestion that Gray has arrived at this level somewhat ahead of schedule, Townsend indicated that, as had been the case with Hogg when he became the first teenager to start a Test for Scotland in 40 years last season, he has proven himself good enough, which makes him old enough.
"He's made his own schedule," the coach claimed. "He's been outstanding at training and outstanding playing for Currie this season and for Melrose in the British & Irish Cup. A couple of weeks ago, I watched his game when Currie played Aberdeen and he was one of the best players on the field. Then he was man-of-the- match at the weekend. It's all down to him, the work he's put in and it's great to be able to bring someone like him on to the bench."
With their captain returning to action having recovered from the gashed arm suffered against Castres, Warriors supporters can, then, relish the prospect of seeing another Al Kellock/Gray partnership forming in their boilerhouse, albeit both Tim Swinson, who starts with Kellock tomorrow and Tom Ryder will have plenty to say about that.
Kellock's return is among four changes to the pack, with Chris Fusaro's recall at least partly enforced as a result of the hamstring injury suffered by John Barclay last weekend, Rob Harley starting alongside him in the back-row and Ryan Grant returning at prop.
As for the back line, Townsend played down the implications of having to react to the several variables in the Edinburgh line-up saying that for all that he may be new to this, his men have seen it all before.
"I've been told by Shade [Munro, Glasgow's forwards coach] that it was the same last year and that there were last-minute changes, but we've got a good inkling of what team they'll bring on Friday," he said.
"It would possibly affect how we set up. We've obviously looked at what someone like Greig [Laidlaw] and Nick [De Luca] will do if they're defending compared with the other two. You've got to have two plans now you know those two might not be playing. You look at what the opposition have in terms of personnel, but it's more about us being us and doing what we can do with the ball."
Certainly, Glasgow have done more when it matters in the derbies in each of the last three years and while Edinburgh have the RaboDirect Pro12's best finisher in Tim Visser, tomorrow's home team are lining the man they hope can match him directly up against him, the only change to their back line seeing Sean Maitland switch to right wing to accommodate the return of Peter Murchie at full-back.