ARSENE WENGER hit back after his own fans turned on him in unprecedented scenes at The Emirates. Never before has the Arsenal manager been so roundly booed by the Arsenal terraces. Never before has a substitution that he made proved so unpopular. It was, however, a substitution that proved so wrong.Taking off flying young winner Alex Oxlade-Chamberlain after 73 minutes was the last straw for the fans who have shown remarkable patience with their manager during six years without a trophy. Wenger's decision came just THREE MINUTES after the outstanding Oxlade-Chamberlain, 18, set up Robin van Persie to cancel out Antonio Valencia's first-half goal. But Wenger snapped: "We lost the game just now and I do not have to explain to you what I do. "I have to stand up to the result and the subs. I've been 30 years a manager and made 50,000 subs and I have to justify every decision I make to you? I stand up for it." Nine minutes after 'The Ox' was replaced by Andrey Arshavin — with emotions running high — the boos got even louder. Arshavin, hardly the most popular player with the fans, hopelessly bought Manchester United winger Antonio Valencia's dummy as he set up Danny Welbeck's winner. Wenger was clearly struggling to keep a lid on his emotions. Particularly when asked about Van Persie's reaction to the substitution. The Dutch striker looked horrified and was clearly seen shouting 'oh no' as the change was made. But Wenger snapped: "I didn't see it. I do not want to come out and have a reaction." The Frenchman was then pushed on whether his decision cost Arsenal the game — as most Gunners fans felt. He replied: "Why? If you expect me to blame an individual player, it will not happen. "We win and lose together. You want me to blame one player? I will not. If I made a mistake, I'm sorry. "I'm like a player. It could have happened as well if Alex had stayed on. That's part of United being dangerous on the flanks." But what of the fans' angry chants for Wenger to spend some money? SunSport revealed last week that despite being forced to field a makeshift defence in the absence of his four injured full-backs, the Arsenal chief would not sign cover. Arsenal have lost three on the bounce at Fulham, Swansea last week and at home to United yesterday with their defensive problems clear for all to see. Wenger added: "Spending the money is not the target. It never has been in life. We need players back." Before the game Wenger insisted failing to qualify for the Champions League would be a 'disaster'. After the morale-sapping defeat, he said: "It leaves us in a very difficult position. We couldn't afford to lose." United manager Alex Ferguson admitted it was their plan to target Arsenal's makeshift full-backs. He said: "That's been their problem for a few weeks — that is a disappointment for them without natural full-backs like Sagna and Gibbs. "They are playing centre-backs out there so it is difficult for them." Visitors United wasted numerous chances and allowed Arsenal back in the game in the second half. Fergie added: "It was an amazing amount of opportunities we had. "It's always difficult coming here, Arsenal are a top side. To create that amount of chances and only score two, we're a bit disappointed."  THE SUN .