Marcelo Bielsa has accepted full responsibility for the Leeds United spying scandal but showed no remorse in a remarkable defence of his actions.
The Football Association (FA) is to investigate the incident after Derby County - ahead of Friday's Championship clash between the clubs - claimed a man caught by police acting "suspiciously" near their training ground was a Leeds employee.
Law enforcement personnel were called to Derby's training centre on Thursday after concerns about the behaviour of the individual outside the premises.
Police confirmed a man was found and questioned at the perimeter fence of the complex, before being sent on his way with no arrest made.
Media reports claimed the man involved was a "spy" sent by Leeds and Bielsa confirmed those allegations, revealing that he personally sent the man in question without notifying the club.
"It's true that there was someone from Leeds," Bielsa told Sky Sports. "The responsibility is with me.
"There are some decisions I need to give, it doesn't matter if it is legal or not. For me it is enough that Derby and [Rams boss] Frank [Lampard] felt it was not the right thing to do and that we didn't behave well.
"Yesterday I talked to Frank and, for him, he felt I didn't respect fair play rules. I have a different point of view on it.
"But the important thing is what Frank and Derby think of it.
"I'm the only person responsible for it because I didn't ask the permission of the club to do it.
"Without trying to find a justification, I've been using these practices since the qualifications for the World Cup with Argentina.
"This is not unlawful, we've been doing it publicly, we talk about it in the press. For some it's the wrong thing and for some it's not."
Thursday's discussion between the pair did little to placate Lampard, who struggled to hide his anger in his own pre-match interview with Sky.
The former Chelsea and England midfield also claimed Leeds sent a spy to Derby training before the sides met in August at Pride Park – a game United won 4-1.
"If we're going to start talking about 'culturally I did it somewhere else and it was fine', then that doesn't work for me because I don't believe it is fine on that level," Lampard said.
"It's disrupted our build-up to this game and the unfortunate thing for us is it disrupted us at our end without us doing anything.
"People are going to say I'm standing here trying to make an excuse pre-game – I will speak like this after the game and more if I have to, win lose or draw, because of what's happened.
"What I will say is we were training the day before the game on team tactics, team shape, personnel, how we're going to press, how we're going to work off the ball.
"If somebody wants to say that's not relevant and that won't affect a game… if tactics aren't relevant then Pep Guardiola, [Mauricio] Pochettino, Jurgen Klopp and all the great managers, they're just lucky."
Lampard added: "Obviously it's not just Derby County. We had somebody the day before our first game against them that we lost 4-1.
"Now, Leeds can beat you 4-1 – they're a fantastic team. But we had someone in the bushes that day. It's twice this season now.
"The man was asked to leave but it wasn't followed up like it was this time."
Leeds are top of the Championship table despite losing their past three games in all competitions, while Derby occupy the final play-off spot in sixth.
|Nuno fined over pitch celebration in Leicester win|
|Nadal unfazed by another Next Gen opponent in Tsitsipas|
|Ulster hand lifetime ban to spectator after Zebo abuse|
|Phehlukwayo´s career-best day inspires Proteas against Pakistan|
|Bournemouth pounce for Brentford´s Mepham|
|You say all signings are controversial – Valverde defends Boateng arrival|
|Search for missing Sala plane suspended|
|Kohli and Williamson display mutual respect as India and Black Caps prepare for battle|
|Qatar 1 Iraq 0: Al Rawi free-kick books quarter-final spot|
|Ba joins Adebayor and Robinho at Istanbul Basaksehir|
|BREAKING NEWS: Tottenham´s Alli out until March with hamstring injury|
|Fit-again Joseph added to England squad|
|It is very, very serious for us - Tuchel wants midfielder in January window|
|Lakers expect Rajon Rondo back Thursday as LeBron James continues rehab|
|Atletico Madrid boosted as Koke thigh injury revealed to be minor|
|South Korea 2 Bahrain 1 (after extra time): Kim Jin-su seals quarter-final spot|
|AC Milan confirm Zapata thigh injury|
|I miss him a lot - Guardiola confirms ´clever´ Mendy back in Man City squad|
|Tiafoe wants LeBron meeting after run to Australian Open quarters|
|Cardiff continue to ´pray´ for Sala|
|West Ham fined over Burnley clash chaos|
|Knicks star Enes Kanter frustrated by reduced role|
|Kvitova getting back to her best, says Barty|
|Kvitova revels in first semi of ´second career´|
|Messi´s the best player in every world – Boateng dismisses past Real Madrid comments|
|Thunder frustrations continue against Renegades|
|Alonso vows to clear name in tax fraud case|
|Classy Nadal downs Tiafoe to set up Tsitsipas semi|
|Hoedt leaves Southampton for Celta Vigo on loan|
|Melbourne City 4 Western Sydney Wanderers 3: Hosts edge thriller with two goals in last six minutes|
|Wilder won´t even pick up the phone - Hearn not hopeful of AJ bout|
|Sala was on board missing plane, say French authorities|
|Arsenal´s Bellerin out for season with ACL rupture|
|Gatland waiting on ´concrete´ offers|
|Ronaldo accepts prison sentence and €18.8m fine for tax fraud|
|Tsitsipas: It was vital to back up Federer win|
|Awesome Kvitova ends Barty´s home run in Melbourne|
|CA rejects Thunder appeal for full points in abandoned Heat clash|
|Emiliano Sala: Concerns grow for Cardiff striker after plane goes missing|
|Harden unimpressed with refs in Rockets´ 76ers disappointment|
|Ronaldo arrives for sentencing in tax fraud case|
|Record-breaking evening ´one of those nights´ for Warriors star Thompson|
|Hazard still interested in Real Madrid but won´t rule out Chelsea stay|
|Collins moves past Pavlyuchenkova, into Australian Open semis|
|Kohli makes history with ICC awards sweep|
|Thompson sets NBA record with 10 straight made three-pointers to open game|
|76ers hand Rockets largest loss of season, Harden scores 37 points|
|Tsitsipas overcomes Bautista Agut to continue Aus Open run|
|Barcelona move a ´dream come true´ for Boateng|
|Rams coach McVay on Gurley: I´ve got to get him more opportunities|
|Butler´s sprained wrist not expected to keep him out ´long term´|
|Saints owner Benson will ´aggressively pursue changes in NFL policies´|
|Levante to take Copa case to CAS|
|It can happen – Allegri plays down Ronaldo penalty miss|
|Mavericks´ Doncic becomes second-youngest player to record triple-double|
|Yankees send Sonny Gray to Reds|
|Ashley Cole reunited with Frank Lampard at Derby County|
|Arnold ready to mix things up in 2019 Asian Cup quarter-finals|
|Arum: Joshua desperately needs to fight in the United States|
|South Korea v Bahrain: Bento optimistic of continuing unblemished campaign|
|Bolton Wanderers 0 West Brom 2: Baggies bounce up to third after tennis ball protest|
|Confident Moeen ready to shine for England in the Caribbean|
|Juventus 3 Chievo 0: Allegri´s men cruise despite Ronaldo penalty save|
|Boateng completes shock Barcelona switch|
|United Arab Emirates 3 Kyrgyzstan 2 (after extra time): Khalil penalty sets up Socceroos showdown|
|West Indies add Drakes to new-look coaching team|
|Barcelona is a huge opportunity – Boateng confirms shock move is close|
|Donnarumma wishes Higuain luck ahead of expected Chelsea switch|
|Qatar v Iraq: Katanec anticipating ´huge challenge´ in last 16|
|Nuno hit with FA misconduct charge for pitch celebration|