PARIS: Cristiano Ronaldo, Lionel Messi and the rest of the world's top footballers may earn eye-popping salaries but the sums they make from long-running boot deals can be equally astounding.
In July 2017 the new face of French football, Kylian Mbappe, pursued by Europe's elite clubs, caused a frenzy of excitement by announcing on Twitter he had a big announcement to make.
Would he choose Real Madrid? Paris Saint-Germain?
But what the 19-year-old actually had to announce was that he was extending a deal he first signed with Nike at the age of 13.
And within weeks he had moved on loan from Monaco to PSG, who are also sponsored by Nike.
It's not just a case of lacing up the customised boots and picking up the fat cheques though -- the high earners are brand ambassadors and have stringent public relations commitments.
"It's not like having a job and being an employee working for an employer," explains image rights specialist Frank Hocquemiller.
"But with a sponsorship deal there come certain obligations. If you have signed a deal with Adidas, Nike or Puma, it means they have bought your image rights.
"It comes with a certain amount of public relations requirements and social network management."
Harnessing Instagram
The aim of sportswear companies is clear -- raising visibility for their product, and they believe paying millions is worth it.
"The sportswear companies are investing more and more money and they want a return," explains Kevin Geoffroy from Footpack.fr, a sportswear news site.
So Twitter, Instagram or Snapchat accounts of the stars are harnessed by the sportswear giants to push their product.
Arsenal and Germany midfielder Mesut Ozil recently advertised Adidas on his Instagram account, where he pointed out he had a paid relationship with the German brand. That pay is reportedly in the region of £3.7 million (4.19 million euros) a year.