Martin O'Neill reflected on a missed opportunity as Aston Villa were denied a first double over Manchester United for 55 years as the 10-man Red Devils held on for a 1-1 draw.

Villa, who won 1-0 at Old Trafford in December, had to settle for a share of the spoils despite the first-half dismissal of Nani after Carlos Cuellar's opener was cancelled out by a James Collins own goal.

United winger Nani was red carded for a two-footed challenge on Villa captain Stiliyan Petrov, who suffered an ankle injury, leaving the visitors facing an hour with 10 men.

O'Neill was slightly frustrated by his side's inability to take all three points.

"When United had a man sent off I was hoping we would be able to take the initiative," said Villa boss Martin O'Neill. "In the second half we didn't create enough really and didn't make enough use of the extra man.

"But we were playing against a real quality side, who have been in that situation before, and who have been able to retain possession.

"We could definitely learn something from that and through replaying the match itself, watching the DVD, we will certainly be able to.

"But, I suppose, if you'd asked me at the start of season would you take four points against United, I'd have been pretty happy with that."

O'Neill believes Villa can go into the February 28 Carling Cup Final against Sir Alex Ferguson's side full of confidence.

"The final at Wembley will be a different set of circumstances, a different environment," he added. "I don't want to think about the final too much because we have got plenty of games before that.

"When it comes round, we should go into the game with plenty of confidence because we have done pretty well in the two results."

O'Neill feels referee Peter Walton was right to give Nani the red card after a challenge which leaves Petrov doubtful for Sunday's FA Cup tie at Crystal Palace, although the injury is not expected to mean a long-term absence.

O'Neill said: "It was a red card. I've always been one in favour of outlawing two-footed challenges. Stiliyan is pretty sore at this minute. He thought he was going to be okay at half-time and said he would continue on, but he stiffened up.

"He was unable to continue and it must be really sore if he was unable to continue. Will he be fit for Sunday? I don't know yet. I am sure there must be some sort of doubt about it, but we will see.

"The doctor said he just thinks it is a lot of soft tissue, whatever that means, but he doesn't think there is any serious damage in that sense."