Monaco are set to receive €180m for Mbappe, but they've also lost a major part of the team which helped them to become French champions last season. Mendy, Bakayoko, Bernardo Silva have all departed...with Fabinho and Lemar rumoured to be joining them out the exit door.
Even so, there have been no signs of panic at the Monegasque club, who already made it clear with a 6-1 dismantling of Marseille that they don't miss anyone. They have strengthened their team and have barely even made a dent into the €100m received from transfers.
In fact, a third of what the sale of Mbappe will earn the club has been used to bring in three young talents with a lot of potential. Youri Tielemans, Stevan Jovetic and Keita Baldé.
The Belgian youngster Tielemans is one of the most promising prospects in his country, he has shined at Anderlecht and was on the radar of all the top clubs around Europe.
Jovetic was close to returning to Sevilla, but the project at Monaco was more appealing for him, as well the fact that Monaco were the only club who offered Inter €11m for the striker.
Then there's the signing of Keita Baldé, one of the stand-out players in last year's Serie A who attracted interest from plenty of top teams this summer.
Three footballers with great potential who could benefit the club both on and off the pitch in terms of performance and financially in the present and near future.
These three are the major signings for a Monaco side who are yet to show any signs of cracking in their bid to retain the Ligue 1 crown. They have managed this without spending a huge amount, despite the burden of other clubs knowing exactly how much money you have to spend in the market, a burden Barcelona know all to well.