Mata spent two and a half seasons at Chelsea, winning the FA Cup, Champions League and Europa League before becoming United’s record signing at that time at a cost of 37.1 million pounds ($45.38 million).
He was sold by Jose Mourinho who then became his manager again when the Portuguese joined United this season.
Hughes was a United hero who “performed with distinction” in two spells at Old Trafford, according to the club website (www.manutd.com).
In the first, from 1980-86, he scored almost 50 goals in 121 games but won only the FA Cup before moving to Barcelona and then Bayern Munich.
Returning to United in 1988, Hughes became an instrumental part of manager Alex Ferguson’s first successes. He scored twice in the drawn 1990 FA Cup final against Crystal Palace before helping United win the replay, and two more goals in the European Cup Winners’ Cup final the following year.
After winning the Premier League in 1993 and 1994, Hughes switched to Chelsea in July 1995 where he formed a potent partnership with Gianfranco Zola, again winning the FA Cup and Cup Winners’ Cup in successive seasons.
Juan Sebastian Veron
The Argentina midfielder never quite lived up to his reputation after joining United from Lazio in 2001 for almost 30 million pounds ($36.69 million).
After two moderate seasons he moved to Chelsea for around half that fee but was hampered by injury and poor form.
The Times newspaper once listed the two transfers as being among the 50 worst in Premier League history.
Australia goalkeeper Bosnich had two spells with United, the first as a 17-year-old. He played only three games before going back to his home country but returned eight years later via Aston Villa for a longer run in the team.
In the 1999-2000 season he won a Premier League winners’ medal but later lost his place to new signing Fabien Barthez and in January 2001 joined Chelsea.
His move to Stamford Bridge ended badly with a failed drugs test the following year, after which the club sacked him.