QPR withstood considerable pressure to cancel out Yaya Toure's opener through Bobby Zamora and it needed a quick response from Edin Dzeko to restore City's lead. Ryan Nelsen went close to another equaliser late on but Carlos Tevez gave the scoreline a more convincing look with his fourth goal of the campaign in injury time.
Mancini, for whom the match was his 100th in charge in the Premier League, told ESPN: "I think we played well in first half, but we have one problem at the moment - when we have a chance to score we don't score and the game can change. We had this problem in the first game and against Liverpool."
He added: "In the second half we didn't play well. We were too slow, but in the end it's important that we took three points."
City goalkeeper Joe Hart kept 17 clean sheets last season but Zamora's close-range header means he has still not recorded one this term. But with seven points from three games, captain Vincent Kompany does not think alarm bells should be ringing yet.
The Belgium international said: "No it doesn't matter. We've always proved to be solid come difficult times. Come December, January and February we'll show it. At this time everyone tries to play the game nicely. We left ourselves exposed but at the end of the season we won't do that."
The defeat left QPR still looking for their first win of the season while their former City boss Mark Hughes is still to triumph away from home since taking charge. But Rangers are much changed from the side which narrowly avoided relegation having signed 12 new players over the summer.
Hughes felt his side were unfortunate not to take something from the game. He said: "I think we are a little bit disappointed. In the first half we restricted them to a few chances and the most problems we had were from set pieces. In general play I thought our shape was good.
"But we were working hard without putting them under enough pressure to affect the game going the other way. I thought we addressed that in the second half and really put a shift in and caused them some problems. I thought we were in control of the game.
"Obviously when we equalised it was a real body blow to concede so soon after that. If we had maintained the position at 1-1 maybe we could have caused them even more problems."
Source: PA
Source: PA