"I told the players at half-time that they were better than they were showing. We gave the ball away too much and did not show enough self-belief," he said.
"The second half performance was tremendous. Goals change games and by the end everyone wanted the ball and every player was showing composure on it.
"I'm not bothered who we get in the next round, but we have had two away ties out of three so far and it would be nice to be drawn at home.
"[Defenders] Michael Morrison and Reda Johnson could hardly have hoped for better debuts. We won't get carried away by one performance but defensively we looked very strong."
City boss Keith Millen admitted: "We were weak mentally after falling behind and the dressing-room was too quiet afterwards.
"We looked a bad side in the second half and it showed we still have a lot of work to do over the rest of the season.
"It was a damaging result financially for the club and just how bad we will only know when we see who Wednesday draw in the next round.
"I have sent all my players home with a DVD of the match and will be looking for a response from them at our next training session."
To complete a bad day for Millen, on-loan defender Steven Caulker was forced off after only nine minutes with a hip injury and second half substitute Christian Ribeiro tore a hamstring only 11 minutes after being introduced.
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