Guardiola is concerned about the psychological effect that three defeats in a week might have on his players as they look to secure the trophy.
It will take the title with a win over Tottenham at Wembley on Saturday and a defeat for second placed United against bottom club West Bromwich Albion on Sunday.
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Despite the disappointment of losing to United, City has still only dropped 12 points all season, but Guardiola is remaining cautious.
Below are four talking points from Wembley.
"Then we started to compete, at 2-0 down and we scored to make it 2-1 and started the second half really well, but Manchester City after 90 minutes were better".
His overlapping runs create chances for the City attack, while his pace contributes to solid defensive displays.
James has knack for first-round knockouts
With the regular season now in the rearview mirror, the focus has shifted directly to the playoffs for the Cleveland Cavaliers . The Miami Heat , the No. 2 seed that season, lost to the No. 7 seed New York Knicks in Game 4 of the first round.
Kane is in a stiff competition with Salah for the Premier League golden boot, with the England striker having 25 goals to his name this season behind Salah who leads the goal scorers chart with 29 goals.
Only the injured Sergio "Kun" Aguero was missing among the regular starters.
Guardiola said winning his first Premier League title would match anything he achieved at Barcelona and Bayern Munich.
A week after spoiling City's title party, United duly handed the league to their local rivals.
On the other hand, Tottenham needs to continue picking up points to ensure a Champions League finish for a third consecutive year.
Ilkay Gundogan stepped up and made no mistake from the spot, 2-0.
"In football, until you get or you achieve what you want, never in football is it over until the end". Each team is among the top six in the EPL in scoring and the over on the 2.5 total is well-priced at -105.
"It's more hard (to win in England)". Eriksen and Alli tried their best to infuse energy and creativity into the team's play but they were unable to break down an organised opposition defence, with the main man Kane forced to feed off scraps and marked out of the game by Vincent Kompany.
Harry Kane will be expected to return to the starting line-up for Spurs after he marked his return to action from an ankle injury with a controversial goal. Gundogan does lack the defensive aptitude that Fernandinho has and Pep accounted for this by pulling Fabian Delph into the midfield from his left back position for much of the game.