Veljko Paunovic hailed Reading's "most complete performance" this season as the Championship leaders defeated Blackburn 4-2 to move seven points clear.
Reading gave Rovers a taste of their own medicine with a goal frenzy that included their fastest ever from Yakou Meite after only eight seconds.
Armstrong's glancing header gave hope of a comeback but Lucas Joao's second goal in a matter of days put the result beyond doubt.
Reading have won three of four on the road this season, and after their second ever win at Ewood Park, Paunovic was delighted the performance came on this ground.
He said: "I feel very, very proud of the guys, especially because of this fantastic game and performance came at this monument of football.
"This stadium is very known and to me, since I was young and dreaming about playing one day here. But now as a coach and coming here first time and winning with a fantastic team and spirit that we have in our group, it's unique.
"And that uniqueness is something we want to keep fostering and cultivating. So far, it's been fantastic. I'm full of gratitude to this group.
"When you look individually, everyone had a fantastic game. Today, I would give the best note to the whole team individually and as a team.
"The adjustments in the second half after the knock Meite received were important. The guys that came in, you don't feel that anything changes. So far, I think it's the most complete performance so far."
Tony Mowbray saw plenty of positives, but conceded Blackburn's defence "fell a bit short."
He said: "I think their forwards were pretty good tonight. We recognised that this week and we had to obviously perform better defensively than we did.
"There were a lot of positives for us, but I think you can't defend like we did, as our defenders did tonight.
"Fell a bit short, I think. Lacked a bit of confidence against the physicality they were playing against and the deeper they dropped because of that physicality didn't help our team, playing as we play.
"We were much better second half. Genuinely felt the first time they crossed the halfway line in the second half they scored, which was 30-odd minutes in. Lots of positives. I think we can score goals, we're a threat, and yet we didn't handle their strikers tonight.
"I don't know the shot stats but there's enough to keep us encouraged and we'll win a lot of games this year."