Carlo Ancelotti has worked for some of the most powerful men in the world but has admitted ex-Chelsea owner Roman Abramovich was the most fearsome taskmaster.
Ancelotti was in charge of the Blues between 2009-11 and won the double in his first season in charge before being sacked by his ruthless boss the following season.
Abramovich was forced to sell Chelsea in May 2022 after he had been sanctioned by the UK government following Russia's invasion of Ukraine - due to the owner's close ties to Vladimir Putin.
Ancelotti, who is now Brazil manager, has worked for former Italian prime minister Silvio Berlusconi at AC Milan, Florentino Perez at Real Madrid and PSG head honcho Nasser Al-Khelaifi.
But he says none come close to the looming 'shadow' of Abramovich and the extreme pressure he felt his job was under during his time in west London.
'I knew my record would get me only so far,' he says in his latest autobiography, 'The Dream - Winning the Champions League'.
Carlo Ancelotti celebrates the Premier League title with Florent Malouda in 2010 - the Italian won the double in his first season at the helm but was sacked in 2011
Former Chelsea owner Roman Abramovich, pictured at a game in February 2010 during Ancelotti's tenure, would visit the training ground after defeats demanding answers
'Abramovich made clear he wanted me to win the Champions League with Chelsea and for Chelsea to carve out its identity on the pitch.
'But now I was working for a Russian oligarch who I suddenly understood expected everything to go well all the time.
'And if it didn't, he wanted to know why. It was my job to supply the answers.'
After an unexpected 3-1 defeat by Wigan, Ancelotti started to appreciate just how hands-on and demanding Abramovich could be.
'This was when the first hint of a shadow fell across my time at the club,' he said.
'Abramovich was at the training ground the morning after demanding answers. What had gone wrong?
'I never had this level of surveillance from Berlusconi. He was a demanding owner and sometimes bought players I didn't need and expected me to fit them into the side or argue about tactics.
'But for a lot of the time he was Prime Minister of Italy so there was no micromanagement. He had more important things to think about.'
Jose Mourinho' (left) led his Inter Milan side to victory over former club Chelsea in a hugely damaging Champions League defeat in March, 2010
Ancelotti spoke in depth about working for Abramovich in his new book (above)
And Ancelotti also revealed that Abramovich was furious after the man he'd sacked, Jose Mourinho, steered Inter Milan to a 3-1 aggregate win over Ancelotti's Blues in the Champions League.
Ancelotti said: 'The next day Abramovich didn't talk just to me but to the whole squad.
'My problem was that Mourinho's triumph was not great for my relationship with Abramovich.
'I was supposed to be the antidote to Mourinho - calm, measured and able to revive the squad after the drama.
'According to Abramovich, Mourinho was supposed to be a spent force.
'Allowing him to disrupt the script. I had embarrassed the owner. Success or failure in Europe is how I would be measured by Abramovich - and the Champions League cost me my job.'
He was dismissed at the end of the 2011 campaign having riled his boss months earlier by subbing off Fernando Torres at half-time of another Champions League defeat.
Ancelotti reflected: 'Torres was his personal decision and substituting him was a direct rebuke to the owner. Momentarily, I had forgotten that, ultimately, you can't beat the owner.'
Chelsea finally went on to win the Champions League the following year, beating Bayern Munich on penalties in the final.
Ancelotti was popular among the Chelsea players during his time at the club
Ancelotti says Abramovich had felt like Mourinho was a spent force when he left the Blues
Abramovich's tenure came to a grinding halt when he was forced to sell the club to Todd Boehly and Clearlake three years ago.
Full proceeds from the £2.5bn sale remain frozen in a UK bank account and proceeds were supposed to be used to help victims of the war in Ukraine.
Earlier this year, a Foreign, Commonwealth & Development Office spokesperson said: 'This government is working hard to ensure the proceeds from the sale of Chelsea FC reach humanitarian causes in Ukraine as quickly as possible.
'The proceeds are currently frozen in a UK bank account while a new independent foundation is established to manage and distribute the money.
'UK officials continue to hold discussions with Mr Abramovich's representatives, experts and international partners, and we will double down on our efforts to reach a resolution.'