Football super-agent Jorge Mendes is due to be questioned by a Spanish judge for the first time Tuesday as part of a probe into striker Radamel Falcao's alleged tax evasion, just one of his clients to fall foul of the country's judiciary.
As Spanish authorities tighten the net around footballers - with Real Madrid superstar Cristiano Ronaldo, another Mendes client, the latest to be accused of tax evasion to the tune of 14.7 million euros ($16.5 million) - their advisers and agents are coming under scrutiny too.
Monaco's Falcao is suspected of failing to correctly declare 5.6 million euros of income earned from image rights between 2012 and 2013 while he was at Atletico Madrid.
The Colombian is accused of using a web of shell companies in the British Virgin Islands, Ireland, Colombia and Panama to avoid taxes on the image rights income.
Mendes is due to appear before a court at Pozuelo de Alarcon, near Madrid, as part of the investigation, but his company Gestifute has already denied any wrongdoing.
"Neither Jorge Mendes nor the company he manages, Gestifute, participate in or offer any service linked, directly or indirectly, to financial, fiscal or legal advice to their clients," it said earlier this month.
Falcao is but one of Mendes' clients to run into trouble with Spain's judiciary.
Ronaldo himself, the world's highest paid athlete according to Forbes, is due to be questioned by a Spanish judge on July 31 over alleged tax evasion.
Fabio Coentrao, the Portugal international who also plays for Real Madrid, is suspected of having hidden close to 1.3 million euros in revenues.
And Manchester United manager Jose Mourinho, another Mendes client, has been accused of failing to pay millions of euros in taxes during his time in charge of Real Madrid.
In this case though, Mendes' company Gestifute said Mourinho had resolved the situation with tax authorities.
Mendes, a 51-year-old former nightclub manager, found himself in the eye of the storm last year in the "Football Leaks" media investigation into alleged soccer corruption.
Based on millions of documents, the investigation claims he offered his clients ways to avoid paying taxes on some of the money they earned.
According to the EIC media consortium he allegedly helped his clients evade a total of 185 million euros in advertising revenues "via a network of shell companies and offshore accounts in Ireland, in the British Virgin Islands, Panama and Switzerland."
Mendes, who is very discreet and rarely gives interviews, has vigorously denied any wrongdoing.
Born to an oil industry worker in Lisbon, Mendes left the Portuguese capital aged 19 to enter the business world in the northern provincial town of Viana do Castelo.
A video rental business which he opened became a successful venture and soon he would meet Portugal keeper Nuno Espirito Santo in a disco he was also running.
A former semi-professional footballer himself, Mendes set about cultivating close links to players, creating his own network and starting to look afer their interests.