"Second half we pummelled them, had a lot of good chances and didn't get any.
"We are camped in their box and if we take one of those chances then the game would have probably changed. It's just one of those days it wasn't going in."
However, he also paid tribute to the spirit shown by Martin O'Neill's team, who defended with great skill in the second half.
"Every man jack of them has put in the extra 10 yards to get to the ball. We closed them down but it was a very strong effort from them."
Ferguson remained calm about his team's chances of retaining their Premier League title.
"It's not an easy league. I say that time and time again. If we get to January within touching distance of the leaders then we're in with a great chance."
A delighted O'Neill said his team had played "cleverly".
"There is a good confidence about the team and great ability," he said.
"There's a fine set of players coming through. If on the day we're capable of scoring goals then I think we have a chance. Just recently we've tightened up a wee bit and that's made a marked improvement.
"Manchester United penned us in and that caused us a few problems, but when we broke we still had a little chance to do something.
"We had a bit of luck when Wayne Rooney hit the bar and perhaps after what's happened in the past on trips here we deserved that little bit of luck.
"It's a great win for us, gives us a boost of confidence but we have a difficult programme between now and the new year."
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