City strengthened their claim for a top-four spot in the Premier League with a 5-0 romp against Crystal Palace at the Etihad Stadium – goals from David Silva, Vincent Kompany, Kevin De Bruyne, Raheem Sterling and Nicolas Otamendi sending them above Liverpool into third on goal difference.
United are four points further back in fifth ahead of their trip to sixth-placed Arsenal on Monday morning AEST, with Mourinho set to ring the changes as the match falls in the middle of his team's Europa League semi-final with Celta Vigo.
Marcus Rashford's free-kick ensured United returned from Vigo with a 1-0 advantage on Friday morning AEST and, although Guardiola might have understandably selfish reasons to want Mourinho's focus to lie elsewhere, he talked up the benefits of the Premier League having its UEFA Champions League representation bolstered for next season.
"We have four teams fighting for two places," he told a post-match news conference.
"Hopefully United can focus on the Europa League and next season we shall see five English teams in Europe which would be amazing."
If City can retain the form that brought the Eagles to earth they should not require any favours from other teams.
Guardiola has regularly complained of his team failing to take their chances over the course of seven draws at home this term and, after seeing a more clinical side to their work, he again wondered what might have been in a season where he will finish trophyless for the first time in his coaching career.
"Tottenham [in a 2-0 win at White Hart Lane last October] is the only team I can think of who created more chances than us [in a game]," he said.
"We are the best team in the league when it comes to creating chances - there is no competition.
"Our problem is finishing these chances - this is the most difficult thing in football. Against United [a 0-0 draw in City's previous home game] we created 19 chances - no goals."
Silva returned from a hamstring injury sustained during City's FA Cup semi-final defeat last month to open the scoring and turn in a virtuoso display, while De Bruyne took centre stage after the break with assists for centre-backs Kompany and Otamendi either side of a strike of this own.
"The teams with the top quality players don't lose the ball in the opposition area. David is one of these players," Guardiola added.
"He rarely loses the ball. Kevin was also excellent and he was unlucky hitting the post again - I think that’s his 10th this season."