The Dons steadied the ship at half-time against Breidablik and went on to win 3-2 in the first leg of the Europa Conference League third qualifying round.
Aberdeen led 2-0 inside 11 minutes after Christian Ramirez and Lewis Ferguson converted Calvin Ramsay corners - the first from a low delivery devised by assistant manager Allan Russell.
The hosts were level following a late first-half penalty but Ramirez grabbed his second four minutes into the second period after Glass made a triple substitution at the break and changed the shape.
Glass told Red TV: "An unbelievable start, a couple of goals from set-pieces that Allan set up. We had limited time but managed to get the work and information in and you saw the players reacting to that. So we were pleased with that.
"Christian is a good player and he knows what he's doing. When you show him things on the video, he understands it. It was a brilliant delivery from young Calvin and it's a great finish as well.
"Not so pleased that we got a little bit loose and allowed them back into the game from being 2-0 up.
"But I think what you saw after that was a great response from the group of players.
"They did really well understanding the change of shape and they got the rewards for their work-rate as well. That was a good team we were playing against."