Louis van Gaal made some big mistakes during his two-year reign as Manchester United manager but none are proving more costly than the signing of Bastian Schweinsteiger from Bayern Munich.
The Red Devils should have known something was up when Pep Guardiola happily allowed the club legend to leave for £6.5million, a paltry fee considering the price they are about to pay for Paul Pogba.
Schweinsteiger had struggled with his form and fitness in each of the last three seasons prior to moving to Old Trafford, but Van Gaal didn't seem to care. From what the Dutchman remembered, the German midfielder was a winner, which was exactly what his fractured squad needed.
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Van Gaal had perhaps been hoping for a rise to prominence similar to that of Andrea Pirlo, who moved to Juventus in what was perceived to be the twilight of his career only to experience his best spell of form with the Old Lady.
But it didn't quite work out like that. The injury problems continued and he struggled with the pace of the Premier League. He finished his debut season at Old Trafford with 13 league starts to his name.
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Not a Mourinho player
When Jose Mourinho arrived, Schweinsteiger must have feared the worst. Although with exceptional quality, Schweinsteiger cannot claim to be the kind of player Mourinho likes. The Portuguese demands all-action from his midfielders, expecting them to appear in both penalty boxes whenever required.
Also keen to trim this large squad to around 20 outfield players and three goalkeepers, as many as nine senior players are left facing a summer exit. Schweinsteiger is the biggest name on a list but also, it seems, the least likely to depart.
Although Pogba's impending arrival is likely to end any chance Schweinsteiger has of playing under Mourinho, there is one reason why the 31-year-old will be reluctant to leave: his contract.
Big contract, big problem
Van Gaal handed the German a three-year deal last summer worth in excess of £220,000-a-week. That makes him one of the highest earners at Manchester United with the club still owing him a staggering £23m before the deal expires in 2018.
Reports have credited AC and Inter Milan with an interest while a number of Bundesliga clubs would surely relish the chance to sign a national hero, but none would be capable, let alone willing, to match his deal.
That leaves club executive Ed Woodward in a very awkward position. He can either agree to give Schweinsteiger a hefty payoff to accept a smaller contract elsewhere or allow him to take up space in Mourinho's compact squad.
It is a similar situation to that of Robin van Persie. Van Gaal didn't want him but the striker was earning a cushy £250,000-a-week and seemed determined to stay. To boot, had the striker seen out the remaining 12 months on his contract, he would have activated a £10m loyalty bonus handed to him by Sir Alex Ferguson in 2012.
He eventually found a team to match his wages in Fenerbahce but that did not stop the Dutchman from demanding an incredible £12m pay-off from United to leave. There is no evidence to suggest Manchester United paid the money but the fact they sold him for around £3m pays homage to how weak their negotiating position was.
With Schweinsteiger, the predicament is threatening to become almost identical.