This week saw City's lead at the top increase from 12 to 15 points after they beat West Brom 3-0 on Wednesday while United were falling to a 2-0 defeat to Tottenham.
"We have to try to finish second".
He added: "They are doing so, so well, that they are not letting the others come close".
United could be 18 points adrift by the time they face Huddersfield at Old Trafford on Saturday, with City playing Burnley in the day's early kick-off at Turf Moor. It is open for second, third, fourth but practically closed for the first.
The goal proved out to be the last of the game as Burnley continued to dominate in the concluding minutes of the game and didn't give any chance to City from there to score as the visitors went back with just one point. Manchester City started strong and kept being strong with results and managed to win games even when they didn't deserve.
As well as they performed in the two games at the Etihad and as brilliantly as they played before Christmas, Burnley haven't won in nine matches and with those injuries mounting up, it's very hard to see that run not extending in to double-figures. We are 15 ahead.
"We didn't have any more players", Guardiola said.
"Because of that am I going to say the referee was bad?" Yet, Guardiola is refusing to get carried away as City target a historic four-trophy haul in a packed schedule.
"I think tomorrow is an incredible day to show the respect, the passion for the club, respect for them [the Munich victims], respect for the families", said Mourinho.
While Mendy is in New York, former New York City FC player Jack Harrison made the journey in the other direction, joining City from the MLS club before immediately being loaned out to Championship side Middlesbrough. "With the points we have and improvement we have to last season, in normal conditions it would be a distance that leaves the fight open".