Roberto Mancini refused to blame goalkeeper Joe Hart for wrecking Manchester Citys title challenge as the champions slipped to a shock 1-0 defeat at Sunderland. Manchester City Goalkeeper Joe Hart during the match against Sunderland at The Stadium of Light. Pic/AFP. England midfielder Adam Johnson claimed the only goal against his former club on Wednesday to end Citys eight-month unbeaten away league record. Hart looked at fault as he was beaten at his near post by Johnsons 53rd minute effort to leave City trailing seven points behind leaders Manchester United, who increased their advantage thanks to a late winner in a 4-3 victory over Newcastle. Roberto Mancini However, Mancinis ire was directed at referee Kevin Friend rather than the England keeper, who was nevertheless at fault for allowing Johnsons cross to slip beneath his outstretched left arm. The Italian admitted his side had been soft in crucial areas, but also pointed the finger at the officials as City suffered a third consecutive defeat at the Stadium of Light, a venue where they are winless for almost four-and-a-half years. Mancini insisted Friend and his assistants had enjoyed their Christmas Day celebrations rather too much, after claiming they missed Craig Gardners foul on Pablo Zabaleta in the build-up to the decisive goal from the winger, who ended a rollercoaster two-and-a-half-year spell at City with a £10 million return to his native North-East in pre-season. Johnson was really clever because we all thought he was going to cross. Instead, he shot, he did very well. I dont think Hart was at fault, Mancini said. The City manager was rather less positive about referee Friend and said: The referee ate too much for Christmas. He was not in good form. But that can happen after Christmas when they have a performance like that. Mancini didnt spare his side from criticism, however, as they fell further behind United, and he added: We didnt score and this is our problem. We just didnt score enough goals to win the game. Whenever we had chances, we were too soft. We were too soft in attack, too soft when we got chances, too soft when we shot. Sometimes we didnt shoot when we should have. We wanted one touch more and thats no good.