Chelsea manager Jose Mourinho made the controversial decision to sell Spanish playmaker Juan Mata to Manchester United back in January - but, come the turn of the New Year, Louis van Gaal may find himself in the exact same boat as the Portuguese coach.
Former United boss David Moyes was desperate to land a marquee signing last January and subsequently agreed to pay out a cool £37.1 million for Mata; a first-class attacking midfielder, but the wrong player at the wrong time for the Red Devils.
Mourinho offloaded Mata because he favoured Brazil international Oscar and did not believe the Spaniard possessed either the required pace or defensive mindset to flourish in his team, despite the fact Mata had been named Chelsea's Player of the Year in both of the two previous seasons.
Did Mourinho know Mata would fail at United?
It was a bold decision by Mourinho - and quite possibly one which ultimately cost the Blues the 2013-14 Premier League title, thinking back to just how rapidly Oscar's form deteriorated in the second half of the season - but it was made with Chelsea's long-term future in mind.
Mourinho could see no place in his team for Mata, while the fact he agreed to sell the player to a direct rival - even one which was badly struggling in the Premier League table at the time - was telling.
In hindsight, it seems the Chelsea boss quickly realised that Mata would struggle at Old Trafford and so cashed in on the Spaniard without much hesitation.
Whether Mourinho believed Mata would only struggle under Moyes, or Moyes's successor too, is unclear. But if he did have reservations about Mata as a Manchester United player at the time, he wouldn't have been the only one.
Gary Neville's reservations
Former Manchester United captain Gary Neville publicly expressed his concern that Mata did not fit the Red Devils' philosophy.
"Does he fit with what I would call the typical philosophy of Manchester United? I would say no," the current England coach said at the time. "They would have to change to accommodate Juan Mata in the way they normally play. They normally play with wide players. Sometimes they tuck in, but generally they have wide players and the thing for me is where is he going to play?
"What it could be is the start of something to lead to other things, but typically I wouldn't say he fits."
And so it's come to pass. Mata has, so far, failed to produce his best form since moving to Old Trafford nine months ago. Barring the odd glimpse of brilliance here and there, the Spain international has been largely disappointing, despite having scored seven goals in 18 appearances.
Mata struggling in multiple systems
He has not been as influential as many Manchester United supporters expected he would be - in either system utilised by Moyes or Van Gaal.
Mata was often moved out to the wing by Moyes in order to accommodate Wayne Rooney - or even Marouane Fellaini, as we witnessed in March's humiliating 3-0 home defeat to local rivals Manchester City - but he has been deployed in his favoured role, behind the central striker, by United's current boss.
However in the matches against Swansea City, Sunderland and Burnley it was hard to tell if Mata was even on the pitch. He may have scored in the draw against Sunderland, but that was his only notable contribution.
His first three competitive performances under Van Gaal will have done little to convince the United boss that he deserves to keep the coveted No. 10 spot now that the Red Devils have significantly strengthened.
Van Gaal's selection headache
Van Gaal faces a selection headache after the international break. Assuming that the Dutch coach sticks to his 3-4-1-2 formation, it's difficult to see how Mata gets in.
It's safe to say that Radamel Falcao is now Manchester United's first-choice centre-forward. The Red Devils now have arguably the best No. 9 on the planet in their ranks - and haven't brought him to Old Trafford to spend the season on the bench.
The Colombia international is likely to partner Robin van Persie in attack, with the Dutchman playing in a slightly deeper position, while Rooney - United's new captain - will replace Mata as the team's main playmaker.
Mata does not possess the required attributes to play as a central midfielder, hence why Van Gaal splashed out a combined £103 million on the signings of midfield trio Angel di Maria, Ander Herrera and Daley Blind this summer. So this only leaves one realistic position for the 26-year-old: the subs' bench.
Even if Van Gaal switches to a 4-3-3, which isn't beyond the realms of possibility given United's dreadful start to the season, it's still hard to see where Mata would fit in.
Michael Carrick or Fellaini would probably replace Di Maria in midfield, with the world-class Argentina international subsequently moving to the left-hand side of United's attacking triumvirate and the talented Adnan Janzuaj playing wide-right.
Mata can't move to the wing
Mata is not a winger, as this Sky Sports graphic proved last month. The Spaniard failed to perform when shifted out wide by Moyes last season, but his numbers look much healthier when played in his best position.
Goals scored statistics, however, can be deceptive. Mata may have stuck the ball in the back of the net a few times, but his overall contribution has been disappointing, particularly for a player who cost just under £40 million.
This is the reason why Spain coach Vicente del Bosque has left the playmaker out of his squad for this evening's Euro 2016 qualifier against Macedonia. He simply isn't playing well at the moment.
Mata should leave for his own good
Mata is clearly a popular member of the Manchester United squad - and, by all accounts, a lovely chap to boot - but he may need to leave the Premier League when the transfer window re-opens for the good of his career.
If Van Gaal can't find a place for him then there's no point keeping him at the club. This is a player who, understandably, expects to play every week - keeping him on the bench and using him as a back-up option isn't an option.
There are a host of top European clubs who would be more than happy to take Mata off United's hands in January.
And Van Gaal may need to take a leaf out of Mourinho's book and display similar ruthlessness in order to get Manchester United back to where they belong.
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