Juan Mata's transfer to Manchester United has earned Chelsea a tidy sum but also shows how much faith Jose Mourinho has in Oscar.
Oscar has been one of Mourinho's mainstays this season in that No. 10 position, despite the fact Mata won Chelsea Players' Player of the Year at the end of the last campaign.
A lot of people questioned that and could not believe that Mata was on the bench a lot of the time but Mourinho, like so often before, has been proved right.
Mata is a fantastic player, don't get me wrong, and I'm sure he will show that at Old Trafford, but Oscar has already scored nine times this year in all competitions, assisted five goals, and had a huge impact on the way Chelsea play.
He is very good defensively, too, winning lots of tackles and retrieving Chelsea the ball in forward positions which, of course, makes it easy for them to create chances and I guess that's one of the reasons why Mourinho has preferred him to Mata.
I really like Oscar's tenacious streak and how he is not scared to get involved in the play as well.
He is very slight and defenders and holding midfielders probably lit up when they first saw him, thinking he would be easy to shove off the ball but that is not the case, as he showed in Chelsea's win over Liverpool when he got stuck into Lucas.
Foreign players have been accused of shirking or not being able to deal with the physical nature of English football but that's certainly not something you can say about Oscar, who doesn't just deal with it but seems to enjoy it.
When you've got the ability he's got - as we saw when he scored that wonderful free-kick against Stoke in the FA Cup on Sunday - and like the battle, that's a great cocktail.
I suppose Mata could have figured on the wing for Chelsea as Hazard has been used in a wider position to where he would perhaps prefer to be, but it's hard to argue that Willian and Andre Schurrle haven't made a big impact on the flanks.
Mourinho loves pace out wide, which he had with Arjen Robben and Damien Duff in his first spell at Chelsea, an at-his-best Samuel Eto'o at Inter Milan, and Cristiano Ronaldo at Real Madrid, and he has maintained that view this year.
Willian and Schurrle have been very effective going forward but they also track back and I have been particularly impressed by Willian now that he has settled into English football.
Coming to the Premier League after spells in Brazil, Ukraine and Russia was always going to be hard for the lad initially, but the fact Liverpool and Tottenham also wanted to sign him shows how highly regarded he is.
He got a great goal against Norwich on his debut which would have settled some nerves and he has come along nicely since then to become a regular starter and one of the best players for Chelsea in the last month to six weeks.
Chelsea are looking fantastic defensively as well now - they have kept seven clean sheets in their last nine games, and only let in late on against Man United and very early in that great game with Liverpool - and I think Gary Cahill deserves a lot of credit for that.
So Chelsea should be headed to the Etihad Stadium in a very confident frame of mind, not only are they in great form - although Wednesday's draw with West Ham will be a slight frustration - but they beat City earlier in the season.
They also got a point at Arsenal and, under Mourinho, are masters at going to difficult places and getting the result they need, so you wouldn't back against them doing it again on Monday night.
From City's perspective, though, this match gives them a chance to make a massive statement.
If they win they will be six points ahead of Chelsea with 14 games to go and that is a very decent lead especially for one racking up the goals and streamrolling teams like they are.
If Mourinho's team lose on Monday, they cannot afford any more slip-ups.