Jose Mourinho has completed a successful raid on his old club by signing Nemanja Matic from Chelsea in a reported £40million deal.
The Serbia international is the second player to leave Stamford Bridge for Manchester United in the last three years, with Mourinho having sold Juan Mata to the Red Devils in January 2014.
Only a handful have made such a switch between the Premier League heavyweights and it is safe to say that not all have been a success at their new club.
Here, we take a look at five of the best-known examples.
RAY WILKINS: CHELSEA TO MANCHESTER UNITED (1979)
England great Ray Wilkins became a star at Chelsea more or less from the moment he made his debut at the age of 17 in 1973.
The midfielder quickly established himself in the first team, becoming their youngest-ever captain at 18.
However, after failing to help the Blues avoid relegation in 1979, 'Butch' was signed by United for £825,000 and won the FA Cup in his fourth season at Old Trafford.
MARK HUGHES: MANCHESTER UNITED TO CHELSEA (1995)
Alex Ferguson brought Mark Hughes back to Manchester United in 1988 after largely unsuccessful spells with Barcelona and Bayern Munich.
The Wales international cost £1.5million but justified that price tag by helping to fire United to eight major trophies in seven years, including two Premier League titles and three FA Cups.
Ferguson opted for something of a squad overhaul in 1995 and Hughes was allowed to depart for Chelsea, with whom he won the FA Cup, EFL Cup and UEFA Cup Winners' Cup in a three-year spell.
MARK BOSNICH: MANCHESTER UNITED TO CHELSEA (2001)
Australia international Mark Bosnich had an unhappy time both at Old Trafford and Stamford Bridge.
The former Manchester United youngster returned to the club from Aston Villa in 1999 and won the Premier League in his first season, but the arrival of Fabien Barthez soon kept him on the fringes of the first team.
He left for Chelsea in January 2001 on a free transfer but fared little better, with fitness issues and off-the-field problems limiting his playing time before he was sacked in 2003 after failing a drugs test.
JUAN SEBASTIAN VERON: MANCHESTER UNITED TO CHELSEA (2003)
Signed for a club-record £28.1million from Lazio in 2001, Juan Sebastian Veron was tipped to add more star power to an already formidable Manchester United midfield.
Instead, the Argentine struggled to settle and, after winning the Premier League in 2002-03, he was allowed to join Chelsea - recently bought by Roman Abramovich - for £15m.
However, Veron made only 14 appearances before being sent on loan to Inter and then Estudiantes before he left for his boyhood club permanently in 2007.
JUAN MATA: CHELSEA TO MANCHESTER UNITED (2014)
Soon after taking over at Manchester United, Jose Mourinho claimed that he never really sold Juan Mata while he was Chelsea boss, instead stressing that it was entirely the player's decision.
Mata had found first-team football restricted after Mourinho's return from Real Madrid and he accepted the chance to sign for David Moyes in January 2014 in a £37.1million deal.
A hugely popular figure at Chelsea, where he won the FA Cup, the Champions League and Europa League, Mata has become a mainstay of the United side under three different managers and won a second Europa League title this year.