Eric Black, the Birmingham City assistant manager, was relieved for a fine display after the interval following a "disappointing" first-half performance in Saturday's FA Cup fourth-round tie.
Birmingham drew 1-1 and secured a replay at St Andrew's on February 7 but it needed the arrival of David Dunn as a 67th-minute substitute to inspire the visitors.
Birmingham looked to be in danger of defeat after falling behind to a well-taken first-half goal by Shane Long.
But a triple substitution by Steve Bruce, the Birmingham manager, midway through the second half, in which the attacking trio of Mikael Fors-sell, David Dunn and Neil Kilkenny was thrust into the action, proved to be decisive. Dunn scored late on.
"It was about trying to contain Reading and keep the crowd quiet but we were disappointed with the first-half performance," Black said. "We could have played better and provided more attempts at goal. Reading had a fair bit of the ball and created a bit of pressure but Maik Taylor hardly had anything to do.
"They didn't create any real chances but we didn't either. In the second half I thought there was a really good reaction and we looked more adventurous and creative in the last third.
"Then the gaffer made a few changes which worked because David Dunn has scored with a great finish for us and I think we could have ultimately won the game.
"Dunn looked back to what we know he can be - provoking things and looking forward. He's working extremely hard and we just have to be careful with him."
Black also paid tribute to the central defensive pairing of Olivier Tebily and Alex Bruce. The duo proved capable replacements for Kenny Cunningham and Matthew Upson.
"Alex showed a brave temperament coming in and playing as he did," Black said. "With Steve being the manager it adds an extra bit of pressure. He came into a new partnership with Olivier and both did really well.
"I was particularly pleased for Olivier because it's difficult when you're not playing games regularly to get your timing and distances right but after ten minutes they settled in and talked and communicated well and I think they've got to be happy with their performances."
Birmingham's scheduled match at home to Bolton Wanderers on February 7 will be postponed again.
Black said: "The last thing we need is a replay because it means the Bolton game being put back. Bolton would have been a hard game, anyway, but with two or three of their players away at the African Cup it would have been better for us but we're still in the Cup.