United have confirmed that they have completed the signing of striker Mame Biram Diouf from Molde FK of Norway.
The 21-year-old has been immediately loaned back to Molde where he will remain until January.
The transfer may surprise some after manager Sir Alex Ferguson stressed, just last week that he would not be making any more signings this summer following the arrivals of Michael Owen, Antonio Valencia and Gabriel Obertan.
Gabriel Obertan, a Paris-born France Under-21 international who can fill several attacking roles, will have to wait for his first-team bow, however, as an unspecified minor injury will keep him out of United's forthcoming tour of the Far East.
Obertan underwent a medical on Tuesday and reports in France have claimed he will cost the Red Devils around £3million.
"Gabriel is a player we have tracked for a few years now, but because of his educational programme our efforts to get him here have always been delayed," United manager Sir Alex Ferguson told manutd.com.
"We are delighted to get him now as he is an exciting prospect. We like to get young players and develop them, and we will see that in Gabriel over the next two years."
Bordeaux sent Obertan on loan to Lorient for the second half of last season where he made 15 appearances, scoring one goal.
"I am very happy to join Manchester United," the player added.
"This is a big opportunity for me to play at such a great club. I am very excited to be here and I look forward to proving what I can do."
Obertan scored against England Under-21s in March and took the Most Valuable Player award at last month's Toulon International youth tournament.
He becomes Ferguson's third signing of the close season after Antonio Valencia and Michael Owen, while Cristiano Ronaldo and Carlos Tevez have led the departures in an already eventful summer at Old Trafford.
979: Born December 14, Chester.
1995: Beats the goalscoring record of Kevin Gallen and Nick Barmby for England Under-15s.
1996: Helps Liverpool win the FA Youth Cup in May. Signs professional terms with Liverpool on 17th birthday after previously joining them as a schoolboy.
1997: May 6 - Scores on his first-team debut against Wimbledon at Selhurst Park.
September 16 - Scores on European debut against Celtic in UEFA Cup.
November 18 - Nets his first senior hat-trick against Grimsby in the Coca-Cola Cup.
December 17 - Scores on his debut for England Under-21s.
1998: February 2 - Named in Glenn Hoddle's senior squad for the first time.
February 11 - Becomes youngest England international of the 20th century when he starts against Chile.
February 14 - Scores his first Premier League hat-trick against Sheffield Wednesday. Finishes season joint-top scorer in the Premier League with 18 goals.
May 31 - Named in England's World Cup squad of 22.
June 22 - Scores after coming on as substitute against Romania but England lose 2-1.
June 30 - Scores a sensational goal against Argentina before England bow out of France 98 on penalties.
December 13 - Named BBC Sports Personality of the Year, one day before his 19th birthday.
1999: April 14 - Liverpool announce Owen is out for three months because of hamstring and tendon injuries.
2000: June - Named in Kevin Keegan's Euro 2000 squad.
2001: May - Scores twice in the last seven minutes as Liverpool come back to beat Arsenal 2-1 in the FA Cup final at the Millennium Stadium.
Plays, but does not score, as Liverpool complete a cup treble when they beat Alaves 5-4 after extra-time to win the UEFA Cup.
September 1 - A hat-trick helps England to an historic 5-1 win over Germany in the World Cup qualifier in Munich.
September 26 - Signs a new four-year deal with the Anfield club.
December 17 - Named European Footballer of the Year.
2002: April 16 - Named as stand-in England captain for friendly against Paraguay.
June - Scores goals against Denmark and Brazil during England's run to the quarter-finals of the World Cup in Japan.
2003: April 26 - Scores his 100th Premier League goal, the second of four in a 6-0 rout of West Brom.
June 11 - Making 50th England appearance, captains the side in the absence of David Beckham and nets twice in 2-1 Euro 2004 qualifying defeat of Slovakia at Riverside Stadium.
September 24 - Breaks Rush's club record, scoring his 21st goal in European competition with a header agains Olimpija Ljubljana in the UEFA Cup first round 1-1 draw in Slovenia.
2004: June - Scores one goal for England in Euro 2004 - in the quarter-final defeat to Portugal.
August 12 - Sources close to Real Madrid reveal the Spanish club have agreed to give Liverpool £8million and Antonio Nunez for the services of Owen.
August 13 - Passes medical with the Spanish giants.
2005: May 23 - After scoring 16 goals in his debut season in Spain, states his intention to stay with Real Madrid despite reported interest from Newcastle.
August 3 - After Real Madrid sign Robinho and Julio Baptista, Owen admits he has had "brief dialogue with three or four Premiership clubs".
August 30 - Owen signs four-year deal with Newcastle, sealing £17million permanent transfer.
September 18 - Opens scoring in second game - a 3-0 win at Blackburn - and follows up in the next game with winner against Manchester City at St James' Park.
October 12 - Takes England goal tally to 33 with first goal of the World Cup qualifier against Poland - equalling Gary Lineker's competitive record of 22 for England.
December 17 - Scores first hat-trick for Newcastle in 4-2 win at West Ham.
December 31 - Breaks metatarsal bone in defeat at Tottenham and is ruled out for "several months".
2006: March 24 - Newcastle announce Owen requires surgery to tighten the screw inserted into his foot during the initial operation.
June 20 - Regains fitness to take his place at the World Cup but injures his knee in first minute of group game against Sweden in Cologne and is immediately replaced. Ruled out for at least nine months.
2007: April 15 - Newcastle chairman Freddy Shepherd says Newcastle may seek an injunction to stop Owen playing for England in the Euro 2008 qualifier against Estonia in June.
April 30 - Owen makes first competitive start in over 10 months, playing the full 90 minutes as Newcastle lose 1-0 to Reading at the Madejski Stadium.
September 29 - Owen undergoes a hernia operation, which proves such a success he is expected to return to action in time for England's Euro 2008 games.
2008: January 19 - Appointed Newcastle captain by new manager Kevin Keegan.
2009: May - Finishes the season with 10 goals as Newcastle are relegated from the Premier League on the final day.
June 22 - Confirms that he will not be renewing his contract with Newcastle.
July 1 - Becomes a free agent after his Newcastle contract runs out.
July 3 - Reports link Owen with free transfer to Manchester United and he later signs a two-year contract with the champions after passing medical tests.
Former Liverpool and Real Madrid star Michael Owen has sealed his shock move to Manchester United.
The former Liverpool, Real Madrid and England striker completed a series of stringent medical tests and has signed a two-year deal with the Barclays Premier League champions.
Owen, 29, spent the day at United's Carrington training complex as the terms of his free transfer were thrashed out, after he lapsed out of contract with Newcastle at the end of last month.
Owen had undergone a medical examination on the eve of the move to assess the troublesome knee which had sidelined him for much of his stay at St James' Park.
Despite his previous injury problems the deal represents little risk to Red Devils boss Sir Alex Ferguson, who has been a long-time admirer of the 29-year-old.
"Michael is a world-class forward with a proven goalscoring record at the highest level and that has never been in question," said the United boss.
"Coming to Manchester United with the expectations that we have is something that Michael will relish."
It is believed Ferguson has struck a pay-as-you-play deal which will involve a basic weekly wage enhanced by bonuses.
The player has taken a significant pay cut from the £110,000 he was reported to be on at Newcastle, for whom he scored 10 goals as they were relegated to the Coca-Cola Championship last season.
But it is the lure of playing for the champions, with the promise of Champions League football again, which excites Owen now as he tries to force his way back into the reckoning with England coach Fabio Capello.
Owen admitted United's approach came as much as a shock to him as it did the rest of football.
"I had just begun to talk to other clubs when out of the blue Sir Alex phoned me and invited me to have breakfast with him next morning during which he told me that he wanted to sign me," he said.
"I agreed without a moment's thought. This is a fantastic opportunity for me and I intend to seize it with both hands.
"I am now looking forward to being a Manchester United player and I am fortunate that I already know so many of the players here.
"I want to thank Sir Alex for the faith he has shown in me and I give him my assurance that I will repay him with my goals and performances."
