The Villa boss had targeted the competition as a possible source of silverware and demonstrated his intentions by naming a handful of frontline stars in his starting XI on Wednesday.

There were also six changes from the side which defeated West Brom 2-1 last time out, but the presence of first-team regulars like Ashley Young, John Carew, Stiliyan Petrov and Gareth Barry - back as captain for the first time since his flirtation with a move to Liverpool - was designed to see Villa into the next round.

Instead, Rangers defender Damion Stewart left Carlos Cuellar in his wake to head the Championship side into the fourth round.

"We put enough into the game to win it. It's a wasted opportunity," said O'Neill.

"When the match is in the balance and you don't take your chances there's always a possibility you might concede and we did.

"We were beaten in the game but if we had been played off the park it would have been a different issue.

"It's naturally disappointing to go out of the competition and not to be in the hat for the next round is really frustrating."

O'Neill was less concerned by the significance - or lack of it - in his decision to hand Barry the armband.

Nevertheless, his restoration as skipper - albeit in Martin Laursen's absence - seems to be final proof that relations between the pair are back on track after the midfielder's dream move to Anfield fell through.

"It's nothing. In the scheme of things it's really unimportant," he said of the decision.

"I'm more disappointed about losing the game so the captaincy is not the thing. I was more than pleased to give it to Gareth and he was more than pleased to get it.

"He didn't hold a speech or anything like that over it but he was, I'm sure, pretty pleased. He doesn't give much away but I think he was pleased - as anyone who gets the captaincy at this football club should be."

Victorious QPR boss Iain Dowie was delighted to see his side match - and better - a side he rates as one of the best in the country through hard work and determination.

"People might ask who I want in the next round but there's not too many bigger sides than them," he said.

"We gave it all we had. I can cope with losing to good sides and maybe on another day Villa would have won. But it's not as though our goalkeeper had to make two or three world-class saves and that is testament to the effort they gave."

Dowie praised Villa winger Ashley Young, who was man of the match by some distance despite finishing on the losing side, but also commented on the home side's physical presence.

"Ashley is one of the best wingers in the world," said Dowie.

"He's a top, top winger and he takes some playing that's for sure. But I picked up their team sheet and... well, they're a big side at the best of times, but they brought in Zat Knight and put Marlon Harewood up front.

"We're a big side too but they are the biggest side on the planet."