Aston Villa manager Martin O'Neill challenged John Carew to build on his match-winning hat-trick as Villa came from 2-0 down to dump Reading out of the FA Cup in a thrilling 4-2 quarter-final win.

Villa looked hungover from last weekend's Carling Cup final defeat during a dreadful first-half showing as the Coca-Cola Championship strugglers raced into a two-goal lead with striker Shane Long's double.

But after Ashley Young responded within a minute of the restart, Carew hit a treble to put Villa back at Wembley and within touching distance of a second final of the season.

O'Neill said: "Gabriel Agbonlahor was poorly this morning and had to go home so John steps in and scores a second-half hat-trick which was absolutely delightful.

"John at his hungriest can perform like that.

"He got the equaliser for us and his game lifted two or three-fold.

"Goals give him confidence and the next thing you know he is running the game. He can do that and I want him to perform like that more often.

"I would be delighted if he could score a hat-trick every week but first he needs to find a level of performance which is up there with the best strikers."

O'Neill refused to go into detail over the contents of his half-time team talk but the transformation in Villa's play was remarkable.

After being second best in the first half Villa had taken the lead by the 57th minute as they blew Reading away with a fabulous spell of attacking play.

O'Neill said: "It was a great spell by us just after half-time and we needed to do something because we had played so meekly in the first half.

"I think after all the effort that we have put in in both cups this season, to go out as meekly as we might have done would have been very disappointing.

"But I am delighted with the team, we have showed great character.

"The players are fine players and they knew how second best we were in the first half.

"They didn't need much reminding of that. But I thought Reading played very, very well in the first half.

"They played with no fear and deserved the second goal and I was pleased to go in just two down.

"But some of my players have performed unbelievably well this season and they came to the fore again."

The Royals had already knocked out Premier League sides Liverpool and Burnley and a third scalp appeared imminent after Long marked his return from suspension with a two-goal blast during the opening 45 minutes.

A first semi-final appearance since 1927 looked on the cards until Villa's superb response but manager Brian McDermott remained realistic.

He said: "I thought we played really, really well in the first half and we were good value for a 2-0 lead.

"Our play was excellent and I am looking forward to watching it again on TV. We could even have had more goals.

"But if you are going to lose a game that's the way to do it, especially in the FA Cup.

"We came up against a class side and we needed to keep it tight for the first 10 minutes after the break and we just couldn't do that.

"It wasn't nerves. We came up against players who could be in the Champions League next year.

"They have pace, power and quality all over the pitch and I think we gave them as tough a game as they have had all season.

"We knew at half-time that they were capable of producing something and they certainly responded to whatever Martin said."