Marcelo Bielsa, the famous Argentine coach known as 'El Loco', is known for his meticulous planning and attention to detail when it comes to preparing his teams for matches.
He might have taken it too far this week, however.
Bielsa, as coach of English second-tier club Leeds United has been accused by rival team Derby Country of having sent an employee to spy on its training session ahead of a league match on Friday.
Derby County says police were called to its training ground on Thursday following reports of a man "acting suspiciously outside the premises." Derby said the man works for the "footballing staff at Leeds" and it would hold talks with the club about the incident.
Leeds didn't immediately issue a response.
Police said the man was seen at the perimeter fence, inside which Derby's players were training. British newspaper The Daily Mail reported he had in his possession a pair of binoculars and a change of clothes.
Derby manager Frank Lampard brought an early end to the training session and the club has made a complaint to the English Football League.
Bielsa's Leeds is top of the League Championship going into the match at sixth-place Derby.