Manchester City now have the aura all feared teams acquire: that of the opponents who are never dead in the fight to pull out a result as the clock moves towards full time. The quality Manchester United thought they had patented is present in Roberto Mancini's team who won when a 92nd-minute David Silva cross found Gareth Barry's head to ensure City's Christmas was not spoiled.

Before then, chances had come and gone but none were converted – one of the narratives of the defending champions' season. Reading, the bottom club, looked to have toiled to an invaluable point until Barry's inaugural strike of the campaign.

For a relieved Mancini his side's refusal to give in resembles the serial champions from across town. "This is a good quality, good character," he said when asked if City are like United in their late shows. "It's important that we have this attitude but I don't know if we can win always in the last minute or two minutes – some games can't finish like this."

Mancini added: "We won the championship in the last second. Also we have recovered a lot of games in the last three or four minutes. We know we can change every game right at the end. I think that is a very important quality."

Exhibit A may be Sergio Agüero's winner against Queens Park Rangers on last season's final day that claimed the title, but a glance at results from that campaign and the current one shows a record studded with goals in the closing minutes.

Home or away, Mancini's side have proved their cast iron mentality. In March, they were losing 1-0 at home to Chelsea before an Agüero equaliser was followed by Samir Nasri's winner five minutes from time. City were also 2-1 down against Tottenham Hotspur at Eastlands in January before clawing back to win via Mario Balotelli's 90th-minute penalty.

This season, Edin Dzeko has often been the go-to man. In October, he scored twice on 80 and 90 minutes to move City from 1-0 behind at West Bromwich Albion to victory, and he also scored a vital 88th-minute winner against Tottenham last month after his side had again trailed 1-0.

These salvage missions, though, all point to the worrying stutter in their form. City have managed 34 goals from 18 league games, and Mancini knows this ratio needs improving. He said: "We need to score more but I was confident before this game because against Newcastle [the previous weekend, when winning 3-1] we play very well, we had a lot of chances. If you score [in the first half] against Reading maybe you can score four or five goals but after they defend well."

City lost their unbeaten league record to United in the previous outing at the Etihad so this was a vital psychological win. "It's a big result but before the game everybody thought, 'OK today we can take three points'. But to take three points you need to score," Mancini said. "This is the problem. In the end I think we deserve this three points."

Joleon Lescott may wonder at his future after being ignored for Karim Rekik, an 18-year-old Dutch central defender, who Mancini preferred to fill in at left-back for Gaël Clichy, who was rested as a precaution.

Mancini insists Lescott is still part of his plans. He said: "Joleon is a serious man, he always works hard. He played the last 15 minutes against Newcastle, he played against [Borussia] Dortmund. It's important for him to continue playing and working like he is."

While Vincent Kompany's groin injury meant he was an unused substitute, and Aleksandar Kolarov, Jack Rodwell, Clichy, Maicon, Micah Richards and Nasri all have injuries of varying seriousness, Mancini again insisted he will not recruit in next month's window: "No, I'm happy with our players, it's important that we recover our players that are injured in this moment, we don't know how many players we lose for the African Cup: two players sure, Kolo and Yaya [Touré] and after I don't know if Abdul [Razak] will go. We will see."

For an unhappy Brian McDermott, who thought Barry's winner came from an illegal climb on Nicky Shorey, there was enough evidence to believe Reading can still avoid relegation. "We had a performance with lots of positives," the manager said. "I'm gutted for the fans [over the goal] and they didn't deserve that. I'm gutted now because we deserved at least a draw out of that game today.

"We've just come to a ground where they have spent unbelievable amounts of money, have got amazing players, terrific fans and were champions last season, so I thought we were excellent in the way we conducted ourselves."

Man of the match Gareth Barry (Manchester City)