O'Neill admitted he paid slightly over the odds to sign Young from Watford in January, with the possibility of an initial $20million fee eventually rising to a club record $24m.

The England Under-21 player took time to adjust to life at Villa Park and the higher expectation levels of supporters.

But there were encouraging signs towards the end of the campaign, and Young has continued that form during Villa's pre-season tour of Canada and North America after impressing for his country in the European Championships in Holland.

O'Neill revealed: "I would have liked to have paid less for Ashley in January but over the course of the next three or four years, he will prove worth every penny of the fee.

"I genuinely think that. It is not just because I paid for him and want to try to justify it. Hopefully the justification will come in the next couple of seasons,

"I expected him to take some time to settle down after coming here. It wouldn't have mattered whether he cost us $500,000 or $20m, I would have still said the same thing.

"For him to have come in and taken the place by storm straight away would have been asking an awful lot

"I've got no question that Ashley Young will be brilliant for us and he has been in good form in the build-up to this season. There is no question that he will be a top-quality player for us."

Villa continue their build-up to the new campaign at Stoke tonight with O'Neill still searching for a right-back after the departures of Aaron Hughes, to Fulham, and Phil Bardsley - following a loan spell from Manchester United.

Olof Mellberg has filled the role competently enough in the past when Villa have encountered injury problems but he prefers to play centre-back.

The need for a new goalkeeper has also heightened now that Thomas Sorensen will miss the start of the season with a hamstring injury.

O'Neill's only experienced keeper is Stuart Taylor and he will want to avoid a repeat of last season when he had to loan Gabor Kiraly from Crystal Palace.

Villa have signed promising American teenager Eric Lichaj.

The six-feet tall defender, from Illinois, was formerly at the University of North Carolina and will link up with Villa's Academy at their new Bodymoor Heath training complex.

Lichaj, 18, attracted the attention of Villa with some impressive performances for the United States Under-20 side. He had previously represented his country at Under-17 level.

Villa, who are owned by Cleveland Browns supremo Randy Lerner, have just returned from a two-match tour of Canada and North America as part of their preparations for the new season.