Chinese international Dong Fangzhuo has signed a new contract with the Reds until 2010 and is now eligible to play for United.
Dong, a tall, athletic and speedy forward, will wear the number 21 shirt at Old Trafford and will become the first ever Chinese player to play for the Reds when he makes his competitive debut.
United manager Sir Alex Ferguson has described his eligibility to play as "exciting".
"We're all excited he has eventually arrived and can start playing," he told ManUtd.com. "He sacrificed two and a half years at Royal Antwerp, which showed great patience and determination.
"He is quick and athletic and he can only improve by training with the first team squad here."
The 21-year-old striker signed for United from Dalian Shide in January 2004 and has since spent two years on loan with Belgian side Royal Antwerp.
At Antwerp, he scored an impressive 35 goals in 61 games. Now, having secured a work permit to play in England, he can begin playing competitive matches.
He has pulled on the red shirt before during pre-season friendlies. Last summer he scored the winning goal against Kaizer Chiefs in Cape Town as part of United's tour of South Africa.
