Reading manager Veljko Paunovic urged his players to show more "maturity" after their four-match unbeaten Championship run came to an end with a 2-1 home defeat by Birmingham.
Birmingham deservedly led 2-0 at half-time thanks to a brace of excellent goals in an eight-minute spell from Jon Toral.
Reading rallied after the interval and reduced the deficit in the 61st minute through Yakou Meite.
But after City defender Harlee Dean had been sent off for a foul on Meite – his second yellow card – Reading's 14-goal top-scorer Lucas Joao saw his resultant penalty well saved by Neil Etheridge.
"We have been in these situations in the past when we have been down at half-time," Paunovic said.
"We couldn't come back completely, even though the reaction was positive.
"We have to put ourselves to the next level, the level of maturity, the level when we can deal with adversity.
"But I still think this a fantastic group and I am so happy to work with them.
"I just wish we had started the first half like we started the second half.
"That was the key – the intensity, the conviction, everything.
"We put out the same line-up as the last game. Maybe it was the fatigue, may be a little bit of heavy legs.
"But we didn't look the same as in the last four games.
"The reaction in the second half, though, was fantastic. Our goal came at the right time and our penalty, too.
"After that, we struggled to recover from that mistake [the penalty miss]. It took too long.
"I understand that you can be disappointed when you miss a penalty – as a team – but you cannot afford to give your opponent a chance to come back."
Birmingham picked up their second successive victory – both games away from home – after a six-match winless run.
"We had a very good first half with the ball, created chances and scored goals," City head coach Aitor Karanka said.
"In the second half, when they scored, it became a difficult game. After the sending off, it was even tougher.
"But the spirit that we showed on the pitch tonight. Even those on the bench, who were supporting their team-mates – shouting and helping them.
"It was a game in which to be proud of this group of players. I said a few weeks ago that people should be patient and so it has proved.
"I knew that Jon [Toral] was going to have his time to be good. If he keeps going in this way, he will be very good for the team.
"He has been waiting for his chance. He started the season well, then he got injured and he's now desperate to show what he can do."