You had a good run, David and Goliath, but you may have been temporarily replaced by the story of Calum and Pep. Chelsea's Under-21 coach McFarlane had never managed a senior match in his life. Guardiola was managing his 562nd for Manchester City, and 1,012th overall.
Though it was purely a point that the visitors took from the Etihad Stadium, it was more than anyone expected. Enzo Maresca had exited. Moises Caicedo was suspended.
There was no Wesley Fofana as the defender's temperature spiked on the morning of this match, and no Robert Sanchez after the goalkeeper picked up a muscular problem the previous day.
No Marc Cucurella or Levi Colwill, and it was not clear how many minutes Cole Palmer could manage, his energy sapping as he eventually completed his first full 90 since September.
The away supporters were signing Roman Abramovich's name amid anger towards their ownership, and they discovered here that Liam Rosenior, the manager of their sister club Strasbourg, was flying in from France to hold further talks over becoming their new boss.
And yet, McFarlane picked a result out of all that rubble.
Trailing 1-0 at half-time, he tweaked his tactical set-up. He had noticed how City were pinning Chelsea back, forcing his right winger Estevao Willian to drop so deep that it was leaving the visitors with a five-man defence.
He replaced that Brazilian with another one in Andrey Santos at the break and moved to more of a 3-4-3, with Enzo Fernandez told to position himself higher up the pitch and Malo Gusto switching from left back to right wing back. Chelsea went man to man when City had the ball while Liam Delap was also introduced, under instructions to rattle the City defence and occupy Guardiola's centre backs.
Add all that together and it worked, coming together wonderfully for Chelsea in stoppage time.
Gusto's run down the right-hand side led to his cross, Delap had defenders gravitating towards him, and Fernandez charged into the six-yard box to score. With that, David had frustrated Goliath, and McFarlane was left with one hell of a story to tell the grandchildren one day – deservedly so.
What would be the equivalent in everyday life? Telling your dog walker that he is to tame a lion this weekend? Your accountant that he is filling in for Rachel Reeves, and, by the way, the Budget is due? Your hairdresser that they are styling Lady Gaga and, oh, she's flying in for London fashion week?
McFarlane is highly rated within Chelsea, and for good reason because he has their development side playing some fine football, but this was an almighty ask for him personally.
He was assisted by Under-21 assistants Andy Ross and James Simmonds and Under-21 analyst Adam Keep, and is set to go back to coaching Chelsea's Under 21s once his club confirm Maresca's successor, most likely to be Rosenior in time for Fulham on Wednesday.
But if the 37-year-old academy coach ever fancies senior management for himself, the last few days will have been invaluable, and going unbeaten versus Guardiola after tactically thwarting one of the greats of the game is hardly a bad line for the old C.V.
Blues together
Chelsea tried to show their togetherness as a club here.
Despite being injured, Sanchez, Cucurella and Colwill were at the Etihad Stadium, as was the suspended Caicedo, the quartet supervising the pre-match training drills at the Etihad.
The Blues' sporting director of scouting and talent, Joe Shields, was also going from player to player for chats on the pitch beforehand.
It was all a rather unusual build-up, with a large number of Chelsea's academy staff, including technical director Glenn van der Kraan, formerly of City, here to show support for their Under-21 colleagues temporarily filling the first-team dugout.
Led by James and Fernandez, the players showed their spirit on the pitch also, and when watching back this match, Rosenior will see he has fighters who he can work with.