Manchester United don't often get to buy top players from a direct rival, but when they do it usually works out well.
Robin van Persie was sensational in his first season, and Andy Cole enjoyed a fine career at Old Trafford after signing from Newcastle.
But their greatest transfer coup of all - and the one United fans are praying Juan Mata emulates - is Eric Cantona, who arrived from Leeds in 1992 and changed the course of football history.
Mata doesn't have Cantona's charisma, but he certainly has his quality.
I don't think anyone doubts he is a truly exceptional player, even if he isn't Jose Mourinho's cup of tea. He could create as many chances as the rest of the team put together - and when Wayne Rooney and Van Persie come back they will be a formidable trio.
And as he is well used to English football, there's every reason to expect an instant impact from him.
On paper he's not the player United need. A strong central midfielder is still their greatest need, while their increasingly shaky defence is also in urgent need of attention.
But this isn't just about Mata's individual gifts - it's also about the lift he will give the team.
Last night's penalty shootout against Sunderland was as bad as you'll ever see, almost a perfect representation of the downward spiral United have got themselves into.
In 2010, David Moyes wrote an article about penalties, saying players needed to step up knowing precisely what they were going to do - making the kick itself just a matter of execution.
That sort of clear thinking went out of the window completely last night. United are desperate and completely bereft of confidence.
Mata's arrival will immediately give the dressing room a boost and help sweep away the negativity.
The players know how good he is. They will want to impress him. Someone like Michael Carrick, who has underperformed badly this season, will need to raise his game.
Look at the Mesut Ozil effect at Arsenal. Like Mata, he didn't seem like a perfect fit, but he energised the entire club so that everyone started playing better.
That's not to say United's problems will disappear overnight, particularly in defence - they still need to strengthen, but Mata, Rooney and Van Persie will give them a good chance of simply outscoring opponents.
Moyes and United needed a 'wow' signing after missing out on Cesc Fabregas in the signing, and Mata is certainly that.
It has been a great few days for Jose Mourinho, who has knocked United out of the title race and got a very good price for a player he clearly didn't have time for. Mata didn't do enough without the ball for Mourinho, and that was that.
Chelsea don't exactly need the money, but they do need to think about Financial Fair Play, and £37 million in the coffers will help on that front.
And as an added bonus, Mata could help United take points off Chelsea's title rivals over the rest of the season.
Could he come back to haunt Chelsea? Not this season, but in the future he might if United get it right. They need four more quality signings - a left-back, a centre-back, a midfielder and another wide player.
Despite their current woes they are still a huge club and a huge brand - they have the financial muscle to compete, but they have to find the right players.
It will be a tall order for Mata to match Cantona's influence, but his arrival is a hugely positive development and a potential springboard for United to salvage their season.
- Sports & Recreation
- Manchester United
- Juan Mata
- Jose Mourinho
- Eric Cantona