QPR twice took the lead through Junior Hoilett and then Djibril Cisse, but saw their efforts chalked off by Kaspars Gorkss and an outstanding Nicky Shorey free-kick. Former Fulham striker Pavel Pogrebnyak turned the tie on its head with a late backheel that saw the Royals progress to the last 16, despite him missing a stoppage-time penalty.
"I was proud of my team and the way they came back," said Reading boss McDermott.
"I talked about identity and the last two games in the Barclays Premier League against Spurs and West Bromwich Albion I just feel we have not performed to a level.
"Our identity as a team is what you saw, what we're about, and I know if we perform at that level and that tempo with the way we pass the ball with pace then we are going to be more than capable in this league. No problem. I felt we needed to strip the team back to what we're about, really.
"In the last couple of games our tempo has been slow and we haven't been getting crosses into the box or creating too many chances. We really stripped the side back. We had good conversations in the dressing room and we wanted to get a result and we did that."
QPR return to Premier League action this weekend, looking for a first victory against West Ham, after a night when manager Mark Hughes was left wondering what could have been. The Welshman said: "At 2-1 (ahead) going into the last period of the game we certainly felt we had done enough.
"We had to battle hard for that and credit to Reading because it was a different test. We had to stand up to a physical challenge and they did a pressing game, which I thought for the most part we dealt reasonably well with certainly in the first half. We got the ball down and created a number of good opportunities that we didn't really capitalise on.
"Obviously at 2-1 I felt we were in the ascendancy and had done enough, but it was an outstanding free-kick from Shorey, which he always has the capability of and at 2-2 it was anybody's game.
"We are disappointed with the manner of the third goal because there were too many consecutive errors that led to the lad having space and time to be able to backheel it in our six-yard box. To lose it in that manner is disappointing but it is understandable to a certain extent given the changes and the injuries we have at the back."
Source: PA
Source: PA