It's no secret that Premier League stars can make millions from their football careers, but former Arsenal player Mathieu Flamini went on to make an even greater fortune after retiring from the sport.
But, in the background, Flamini was working on something bigger.
Something that, could not only change the world, but has made him a multi-billionaire.
In 2008, just as he began his brief hiatus from Arsenal to play for AC Milan, Flamini co-founded a company called GF Biochemicals.
For years, he kept the company a secret from those close to him, including his Arsenal teammates.
While playing for AC Milan and Arsenal, Flamini was working hard behind the scenes to build partnerships, secure investments, and pour himself into research to get the company off the ground.
So, what exactly does Flamini's company do?
Well, GF Biochemicals produces a product called levulinic acid, which has been named by the US Department of Energy as one of just 12 key molecules that could help to make a 'greener' planet.
Levulinic acid is a natural and organic preservative but can be used as a substitute for oil in all its forms, which could be essential in reducing carbon emissions and be a huge help in the battle against climate change.
The product can also help to create a biodegradable alternative to plastics, solvents, and detergents that are damaging the planet.
In fact, research by the University of Maastricht has found that levulinic acid could reduce the CO2 made from manufacturing petrochemical products by up to 80 percent.
Not long after he officially hung up his football boots in 2019, he was appointed CEO of GF Biochemicals, with his personal net worth now said to be worth an estimated £10 billion.
And suddenly that Premier League money looks like chump change.
Although the money is definitely a bonus, Flamini insists that it's his passion for saving the planet that has driven him.
To be fair, you'd have to be pretty passionate to set up an operation like this all while playing midfield for one of the biggest football teams in the world.
"I grew up in Marseilles near the sea, and was aware of the environmental questions around ocean plastics and chemical pollution from a very young age," he explained in an interview with Sifted.
“I feel like I’m part of this effort of the younger generation like Greta Thunberg that’s setting up the future."Featured Image Credit: Michael Bowles/Shutterstock/Graham Chadwick/ANL/Shutterstock