Berbatov finally completed a four-year deal to join from Tottenham just before the closure of the transfer window last night, bringing an end to one of the summer's major transfer sagas.

And while neighbours Manchester City might have sent shockwaves across the city with their own pursuit of Berbatov and eventual signing of Robinho, Ferguson is intent on ensuring United remain top of the pile in England.

'This is a key signing,' the United boss told www.manutd.com.

'Dimitar is one of the best and most exciting strikers in world football.

'His style and ability will give the team a different dimension and I am sure he will be a popular player with the fans.'

Berbatov was driven away from Old Trafford just before the announcement of his move was made public. But the Bulgarian was clearly happy as he was pictured inside the stadium and is looking forward to becoming a United legend.

'Joining Manchester United is a dream come true for me,' he said.

'I look forward to playing my part in helping this club win more honours in the years to come.'

After a breathless afternoon, in which Berbatov spent time at United's Carrington training complex and then Old Trafford, he was then taken to a south Manchester hospital for a medical.

With no problems reported, he returned to Old Trafford, where he was greeted warmly by Sir Alex Ferguson and chief executive David Gill to begin the long wait to see if a deal could be done that would eventually see Berbatov wear the number nine shirt vacated by Louis Saha, following the Frenchman's sale to Everton.

Forty minutes before the deadline expired, United submitted papers to the Premier League, hoping the registration would go through in time, with the deal, which will see Fraizer Campbell move in the other direction on a season-long loan, being confirmed at 12.40am.

While the fee is more than United ideally wanted to pay, they have gained agreement from Tottenham chairman Daniel Levy that he will not pursue his complaint against the Old Trafford outfit for approaching Berbatov in the first place.

Having agreed an amazing £35million deal with cash-rich Manchester City, Levy knew he might have pocketed even more cash. However, he was also aware Berbatov had his heart set on joining United having unloaded a player who clearly no longer wanted to be at White Hart Lane and was beginning to unsettle other members of Juande Ramos' squad.

For Ferguson, Berbatov's arrival was a matter of extreme urgency.

While United were always confident Manchester City would be seen off as potential bidders, the evidence of the past two weeks, when Darren Fletcher has been the only player to score in the Premier League and the Super Cup was lost to Zenit St Petersburg on Friday when Nemanja Vidic found the target, Ferguson knew he needed another senior striker.

The Scot has won the last two Premier League titles, and the Champions League a man light of his preferred four-pronged forward line.

And he knew this time around, there would be no surprise signing such as Henrik Larsson to help the Red Devils out, or an unexpected seam of goals from Ole Gunnar Solskjaer, or, due to his current injury, 42 from Cristiano Ronaldo.

Campbell might have impressed in pre-season but Ferguson realised it was too much to expect the youngster to hold down a regular place should either Wayne Rooney or Carlos Tevez be ruled out for an extended period.

And, though other targets such as Michael Owen, Thierry Henry and David Villa were mentioned, Berbatov was the man Ferguson kept returning to.

At 27, Berbatov is slightly older than most of United's recent major purchases but Ferguson feels his silky touch - which the Scot first experienced when Bayer Leverkusen faced the Red Devils in Champions League combat five years ago.

Ferguson believes Berbatov has the quality to score goals himself and create chances for others.

Some may question the player's temperament in light of his recent behaviour but Ferguson has worked with plenty of highly-strung individuals, including Eric Cantona, and got the best out of them.

He will expect to do the same with Berbatov, starting when United travel to Anfield to face Liverpool on September 13.