For a serial winner, no side and no manager has caused Pep Guardiola as many problems as Jurgen Klopp
"I start to read and then I start to think 'Liverpool and Jurgen Klopp' and I cannot focus," said Manchester City manager Pep Guardiola last month, admitting Liverpool's charge to depose the Premier League champions has been in his head for some time.
But in their very first game of 2019, City already find themselves in must-win territory to haul Liverpool back into view by inflicting the leaders' first defeat of the season and cutting a seven-point lead to four at the Etihad on Thursday.
"With the position of Liverpool, if we drop points then it is over, it is finished; it would be almost impossible," said Guardiola after Sunday's 3-1 win at Southampton.
Guardiola's obsession with Liverpool and Klopp in particular is not surprising. For a serial winner, no side and no manager has caused the Catalan as many problems as the German.
City have won just one of seven meetings since Guardiola joined Klopp in England after locking horns in charge of Bundesliga giants Bayern Munich and Borussia Dortmund.
A shock run of three defeats in four Premier League games in December has left City playing catch up to a Liverpool side eyeing history by ending a 29-year wait to win the league.
But even when seemingly no one else could stop City as they stormed to the title with a record 100 points last season, Klopp's men were a constant menace.
'They scare me'
Last January, it was City who were on course to equal Arsenal's 'Invincibles' of 2003-04 until they went to Anfield in January and were blown away by a three-goal salvo in nine second-half minutes to lose 4-3 despite a late rally.
In the documentary "All Or Nothing" which chronicled City's title triumph, Guardiola is seen admitting to his coaching staff ahead of returning to Anfield for the Champions League quarter-final, first leg: "They scare me. They're dangerous, I mean it."
It takes a lot to frighten a coach who has won 24 trophies in three different countries, but Guardiola's fears were realised as another Liverpool blitz secured a 3-0 win.
Six days later, Liverpool won again at the Etihad, withstanding a City onslaught for 45 minutes to take control in the second period once Guardiola had lost his cool and been sent to the stands.
Now Liverpool have extended that ability for short destructive bursts into a title challenge for the long haul.
The addition of Brazilian goalkeeper Alisson Becker and a first full season with the world's most expensive defender Virgil van Dijk has seen Klopp's men concede just eight times in 20 Premier League games.
And after a slow start, the prolific front three of Mohamed Salah, Roberto Firmino and Sadio Mane that terrorised City last season are beginning to hit top form once more.
All three scored in the same Premier League game for the first time this season on Saturday as Arsenal were blown away 5-1 at Anfield.
"Unfortunately we lost two (games) and have a rival that is the best team in Europe or in the world in top form like Liverpool," added Guardiola.
"That's why it is a challenge for us next Thursday to try and win there to try and sustain this position as long as possible to arrive at the end of the season fighting for the title."
However, the City boss has also been keen to reiterate just how good his own side are, despite their recent blip.
Until mid-December City were heavy favourites to back up a record 100-point season that saw them compared to the greatest sides English football has seen with another significant landmark of becoming the first side in a decade to retain the Premier League.
Consistent success is the mark of a truly great side and if City should reel in a Liverpool side seemingly hell bent on making history, that is a tag they will deserve.