Steffen Wohlfarth headed an injury-time winner to complete a storming fightback for a side that found themselves 2-0 down after just 21 minutes.
"Celtic hadn't really done anything and we were 2-0 down," Adams said.
"They were two poor goals from our point of view, crosses into the box and Michael knows he should have done better with both goals.
"We knew we had the quality in the side to go on and do something in the game.
"We got ourselves back in it and thoroughly deserved to win the match.
"Celtic didn't really create many opportunities in the 90 minutes. It was fantastic from our point of view."