Fulham boss Slavisa Jokanovic said his team made too many mistakes after their unbeaten Championship run came to an end with a 1-0 defeat to Birmingham.
The Whites gave away two penalties, with Clayton Donaldson converting his second one in the 49th minute after missing a spot-kick in the first half.
Michael Madl picked up two yellow cards in 44 minutes to make it an uphill battle for Jokanovic's men and the decisive penalty was given away after the London club cheaply lost possession and Floyd Ayite fouled Che Adams.
Despite late pressure, Jokanovic said: "Birmingham played better than we did today and they deserved the points.
"We made so many mistakes during the game and had possession of the ball but not enough with our offensive players.
"If it's one game with so many mistakes then it's my responsibility - we have to continue to work hard. We know this kind of game can happen. Generally we'll try and improve ourselves."
Jokanovic still wants his team to play out from the back, even though his players were frequently caught in possession.
The 48-year-old added: "I want to play from the back, it's generally what my teams try to follow. But we made many mistakes and didn't have enough quality in the game.
"I want to encourage my players and we have to find a solution - we didn't find it today.
"At the end of the game we had chances but after the game the result is realistic.
"We made so many mistakes and didn't play well."
Birmingham manager Gary Rowett, whose side ended the day in fourth, revealed he had put winger Jacques Maghoma on penalty duties after Donaldson's first miss.
But when the second penalty was awarded, Donaldson made sure that he was the man to convert the spot-kick.
Rowett said: "I told Mags (Maghoma) to take the penalty - Mags was meant to take the second pen.
"But fair play to Clayton, he showed a lot of bottle to take it.
"Mags told him he wasn't taking it and they sorted it out between themselves. I was nervous and didn't want him to take it but he showed character.
"The first one (penalty) wasn't bad to be fair, it was an excellent save, and the second time he didn't give him any chance."
Stephen Gleeson was linked with a move away from St Andrews and was not included in the matchday squad.
Rowett added: "Stephen Gleeson was fit but Reece Brown has done so well.
"We played with three central midfielders so I didn't want to bring Gleeson in just because he's a senior player."