Tomorrow's derby double header will have extra spice given the past conflicts between both sets of managers. The Straits Times looks at the key clashes.
Jose Mourinho v Pep Guardiola
Head to head: 4-7-8 (Wins-draws-losses)
A WAR OF WORDS
Although Jose Mourinho's first managerial meeting with Pep Guardiola was when he was in charge of Inter Milan against the latter's Barcelona, it was not until he took over the reins at Real Madrid that the heated rivalry truly began.
In the build-up to the Champions League semi-finals in 2011 between the two sides, the usually more mild-mannered Guardiola cracked.
Barca won the first leg 2-0, but Guardiola clearly showed the world the ill feelings between the two men when he exploded in anger during his pre-match news conference.
"As Mourinho has spoken so candidly about me and spoken about me by name, then I will do the same," the Spaniard said, bristling.
"In this room, he is the chief, the f***ing man. In here, he is the f***ing man and I can't compete with him," he added, referring to how Mourinho was often more vocal with his "mind games".
AN EYE FOR AN EYE
In August 2011, Mourinho poked Guardiola's then assistant, Tito Vilanova, in the eye during a melee in Real's 3-2 defeat by Barcelona in the Spanish Super Cup.
Barcelona's Cesc Fabregas sparked a scuffle after he was on the receiving end of a bad tackle by Real defender Marcelo. Mourinho was incensed by the incident and that resulted in the clash.
In recent years, Mourinho has played down the rivalry between him and Guardiola, saying that it was nothing personal and nothing more than one of sports' greatest battles (the El Clasico between Real and Barcelona).
But Mourinho has once again started the barbs ahead of the Manchester derby today.
The Portuguese said last week that he was "not surprised" when Guardiola received no sanction for stepping onto the pitch after Manchester City's late winner against Southampton in the Premier League.
He refused to explain why he thought so, but implied that it might have been a different case if it was him instead, due to his "poor" reputation compared to Guardiola's.
And just this week, Mourinho also accused Guardiola of lying when he suggested that David Silva might miss the derby as the midfielder was carrying "an unspecified knock".
Jurgen Klopp v Sam Allardyce
'SOFT GERMAN' GETS TOUGH
Liverpool manager Jurgen Klopp admitted that he has "history" with newly-appointed Everton boss Sam Allardyce.
Klopp was called a "soft German" by Allardyce after Liverpool beat his Sunderland team 1-0 in December 2015.
The duo were involved in a heated exchange after Klopp reacted furiously to Jermaine Lens' awful challenge on Mamadou Sakho.
KLOPP TO BLAME
Ahead of Liverpool's trip to Exeter in the FA Cup in January last year, Klopp faced an injury crisis with 13 first-team players out.
Allardyce was quick to attribute the blame to Klopp.
"That is him asking his players to play a high tempo pressing game from the top end," the Englishman said.
"I don't think Jurgen has realised just how ferocious our league is at this period of time."
Klopp responded by saying: "I'm glad for Sam that he is such an experienced manager yet he has time to think about Liverpool. I don't have time to think about this."