Ahead of that encounter at Anfield, Guardiola said the tie against Liverpool would take priority over the derby in his planning, despite the dream scenario of winning the title against United holding obvious appeal in the eyes of many City fans.
Despite leading the Premier League by 13 points, City have come under criticism following back-to-back defeats to Liverpool and Manchester United.
"We are going to have a training session and I will speak with the doctors, the physios and the players and we are going to see tomorrow morning what is the best team. Congratulations to United. Now we're going to try and stand up again and focus on Tuesday". "Nobody believes we will go through".
Speaking after the game, Guardiola said: "We created enough chances in the first half". Second half they arrive twice and score two goals.
And they were even more porous as United fought back to turn the game around in a 16-minute spell just after half-time as a Paul Pogba double and Chris Smalling's victor handed United a famous win.
"When you play against Liverpool, United or in Europe when you have your momentums you have to close the door and we didn't close it".
United stormed back in the second half, though, as a Paul Pogba brace pulled them level and then an unmarked Chris Smalling volleyed in from a free-kick to spoil City's title party. I've dropped a lot of Champions League games in the space of 10 or 15 minutes. It is so complicated because we are going to play a top, top team.
Guardiola said it was not yet clear whether Argentine forward Sergio Aguero would be ready to return from the knee injury which kept him out of action at Anfield.
It marked the first time Guardiola has suffered consecutive defeats as a manager since 2015 during his time with Bayern Munich and there may be concerns his rotational decisions to rest key players for their UEFA Champions League quarter-final may have backfired with a dent in the overall squad morale. You have to defend a little better in the second half, but it is football but.
While the margin of victory was emphatic, Klopp said he had been in the game too long to think the contest was over.
"When you analyse the game, it was good, so I can not expect 30 minutes and the opponent doesn't do absolutely anything".