The England international, 26 next month, passed a medical in Manchester yesterday before putting pen to paper and immediately set his sights on helping United to a record 20th title next season, while also admitting his arrival at Old Trafford was the fulfilment of a boyhood dream.

"To come and play for one of the biggest clubs in the world, it is an opportunity that I couldn't turn down, to play with such great players that play for this club and to hopefully become part of the history of winning the 20th title," Young told MUTV.

"As a child I always wanted to play for one of the biggest clubs in the world and I've got that opportunity now. I've just got to take it with two hands.

"I'm really excited about playing for one of the biggest clubs in the world. I just want to get out there and start training now."

Young became United's second signing of the summer, following Blackburn's England Under-21 international Phil Jones after he was signed for £16.5million almost a fortnight ago.

The forward scored 39 goals in 193 appearances with Aston Villa but, significantly, in the past five Barclays Premier League seasons only Arsenal midfielder Cesc Fabregas has provided more assists.

Despite that, Young admits he faces a tough prospect to become a first-choice winger where he is set to compete with the likes of Antonio Valencia, Nani and Park Ji-sung.

"There's a lot of competition for places at the club," he said. "If you are in the team there is always going to be someone biting away at your heels trying to get in.

"I'm going to be coming in looking to establish myself in the team. I know it is going to be a challenge, but I'm up for that challenge.

"It is a fantastic team. The club always produces fantastic players. They have that winning mentality.

"I hope to be a part of that this season. I can't wait to get started."

Despite United finishing nine points clear of second-placed Chelsea last season, manager Sir Alex Ferguson always knew he would have to make changes to the playing staff.

The retirements of midfielder Paul Scholes, right-back Gary Neville and goalkeeper Edwin van der Sar left huge holes in terms of experience while other exits - such as defender Wes Brown - are expected.

Injury-plagued Owen Hargreaves' release this summer freed up another place in the squad, while veteran midfielder Ryan Giggs will be 38 in November and centre-back Rio Ferdinand has struggled with his fitness over the last couple of years.

To that end the Red Devils boss has moved quickly in the transfer market by bringing in two of England's brightest talents.

In doing so he has also stolen a march on arch-rival Kenny Dalglish at Liverpool, who was interested in both Young and Jones.

The spending will not stop there, however, as next on the list is the replacement for Van der Sar.

It seems likely Atletico Madrid goalkeeper David De Gea will be the one to fill that key position, with Ferguson revealing a few weeks ago United had been working on the transfer for some time.

The 69-year-old Scot is also keen to add more creativity to his midfield as, despite comfortably winning the 12th Barclays Premier League title of his tenure at Old Trafford, his side were comprehensively outplayed by Barcelona in last month's Champions League final at Wembley.

United have been linked with Udinese winger Alexis Sanchez - although Barcelona still seem favourites to clinch that deal - and Inter Milan midfielder Wesley Sneijder.

Villa, who signed Young from Watford in January 2007 in a deal eventually worth £10million, were resigned to losing one of their prize assets as he had only a year left on his contract and had made it clear he was not interested in renewing it.

"Ashley has made a terrific contribution for Villa over the past four and a half seasons and everyone at the club wishes him the best for the future," new Villa boss Alex McLeish said.

"He has become an important player in the England team during that time and I'm sure he will be looking forward to this new challenge."