Frank Lampard insisted he would rather quit coaching than employ the 'spying' tactics used by opposite number Marcelo Bielsa ahead of Derby's 2-0 defeat at Leeds.
The build-up to the Sky Bet Championship match was overshadowed after a man was caught outside Derby's training ground on Thursday.
Derbyshire Police were forced to intervene and it transpired the man was an employee of Leeds who was watching a training session.
Bielsa spoke to Lampard over the phone to accept full responsibility for the incident but the former England midfielder was still unhappy with the pre-match distraction after goals from Kemar Roofe and Jack Harrison secured Leeds a welcome win.
"We lost to the better team from minute one to minute 90 whatever," said Lampard, who joked the Football Association should reverse the three points. "There's no talking around that.
"I'm in a difficult position because I want to draw a line between the performance and the bigger story of what happened.
"Of course I don't think it's right and I'm not sure anyone who's played sport at any level would think it's right. If it's a cultural thing I'm very surprised because I don't think it's right.
"Cheating is a big word. If you talk about details and gaining advantages, great and good managers do that. But this one is over the line. It's not just a toe over the line, it's a hop, skip and a jump over the line.
"All managers are proud of what they do on the training ground. I've spent 15 hours watching Leeds this week and that's the game.
"So when somebody comes in on the sly to see you do team shape, team press and people who aren't playing, it's over the line.
"I was a fan of his from afar and have his book at home. You watch his career and he's very different in a good way, but it's not the way I do things.
"I'd rather not coach than send people undercover on their hands and knees with plyers and bolt cutters to go and look at the opposition because I respect the opposition."
Bielsa insisted it was not his intention to gain an advantage in a lengthy explanation that saw him absolve his club of any blame.
The former Argentina and Chile coach admitted it is a tactic he has employed for a number of years amid claims from Lampard that the same individual was spotted outside the training ground in the build-up to Leeds' 4-1 victory at Pride Park in August.
"I can explain my behaviour but I do not justify it because I have to respect the norms that are applied in the country where I work," said Bielsa, whose side moved five points clear at the top of the table.
"It's something legal in South America and here too. But when it becomes public it doesn't provoke the same indignation as it does in England.
"I don't feel like someone who has cheated by doing that for one main reason: I didn't get any added advantage by watching this session.
"I didn't call him (Lampard) to apologise, I called him to say it actually happened and that I was responsible."
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