Joe Hart bemoaned one of his 'worst days in a Manchester City shirt' following Sunday's derby thumping by Manchester United. The England number one appeared devastated after the final whistle at Old Trafford and acknowledged that City's bid to retain their Premier League title was over. 'That's one of my worst in a Man City shirt, definitely,' Hart said after a morale-sapping 4-2 defeat saw under-fire Manuel Pellegrini's men go four points adrift of neighbours United and 12 behind runaway leaders Chelsea. Manchester City goalkeeper Joe Hart, pictured with Frank Lampard, was disappointed with his side's display . Hart was unable to keep out goals by United's Ashley Young, Marouane Fellaini, Juan Mata and Chris Smalling . Manchester City are four points behind rivals United . The 27-year-old has even given up on knocking Arsenal out of second place. 'It's essential to try and finish third,' he added. 'We've got to get our heads down and win these massive games.' City had looked dominant in the early stages, racing into a 1-0 lead that they could have extended before Ashley Young's equaliser triggered a derby demolition. 'Not many teams have put us to the sword like that,' Hart said. 'United know what they are doing, they took their chances. Hart, pictured saluting the travelling City fans, does not understand why his side are struggling for form . 'It's hard to take. We've won enough of them to know how to lose properly though and we weren't good enough after the first 15 minutes.' Hart added that City had let their fans down and revealed he was at a loss to explain a dramatic loss in form since the turn of the year that has seen them take 18 points from a possible 39. 'It would be easier to win games if I knew what was wrong with us but we've played well and been unfortunate in some games,' he said. 'I'm hurting from this defeat. There's a lot of emotion running through me. Let's see how it feels on Monday, we'll think about it and we'll go again.'
Joe Hart conceded four goals in Man City's 4-2 defeat at Old Trafford .
The Man City stopper appears to have given up on trying to catch Arsenal .
Hart said after Sunday's defeat that 'it's essential to try and finish third'
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