They haven't kicked a ball in anger all week, yet Chelsea have taken a giant stride toward being crowned Premier League champions.
Now it's back to league action this weekend for both teams—the first time since Feb. 22 for City and March 1 for the Gunners.
When they return, however, they will be confronted by a different landscape to the one they left.
While Capital One Cup and FA Cup duties have seen Manuel Pellegrini and Arsene Wenger's attentions focused elsewhere in recent weeks, Jose Mourinho's team has seized the initiative in the title race.
In fact, Chelsea are threatening to run away with it altogether.
Whereas things had been watertight for much of 2013-14, Chelsea now have a seven-point lead at the top and nine on City. While their rivals may have games in hand, the psychological advantage those points give them cannot be ignored.
Nor can the demoralizing defeats City and Arsenal have endured this week.
Had either team overturned two-goal deficits from their first-leg defeats, they would be riding high. The confidence would be oozing, and they would have added a formidable spring to their step. It would be all chests out, fists pumped.
Instead, they have been reminded all the more of their shortcomings, and the clouds of doom have failed to clear. If anything, they've set in more.
All City have left to compete for now is the Premier League, having fallen short against Barca in Europe after Wigan Athletic upset them for the second season running in the FA Cup.
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Pellegrini's side suddenly look beatable, and while confidence is flowing at Stamford Bridge, it appears in short supply in Manchester.
Whereas cup duties could have helped City continue their progress, rolling from victory to victory, it's different now.
They have a major job on their hands to catch Chelsea, knowing the slightest hiccup in any of their three games in hand means significant ground will be lost.
Arsenal have an FA Cup semifinal to look forward to in April, although their record against the big teams this season has been poor, and Bayern's victory will drive home that fact all the more.
"If anything, it should give us motivation," said City captain Vincent Kompany of their defeat to Barca, per Metro.
"The way we played against Wigan [in Sunday's FA Cup defeat], the performance was completely different [...] We’ve got nothing left in the tank."
It's that final analysis from Kompany that is the concern. There's nothing left in the tank, yet Chelsea are escaping over the horizon and must be reined in.
Brave, courageous—any number of adjectives can be thrown at City and Arsenal's endeavors to fight their way back into contention in their respective Champions League ties. The simple fact is, however, that they lost and now the pressure to succeed in the league has been cranked up a notch.
It will be a decade since Arsenal last lifted the trophy. Did Sheikh Mansour really replace Mancini with Pellegrini to get his hands on just the Capital One Cup? We don't think so, either.
Should Chelsea progress in the last 16 of the Champions League next week, they will have extra fixtures to contend with themselves, of course.
They are not playing catch-up, though, while City and Arsenal are. That's vital.
While those teams will be entertaining the likes of Sunderland and Swansea City midweek in their bid to close the gap, Chelsea's European journey will be gathering pace. And should it go the way of the previous two campaigns, the excitement and atmosphere around the club will ensure their season rolls on.
At this stage of the year, every squad needs harmony, the players need confidence and, above all, momentum. Right now, Chelsea have all three in abundance.
What have City and Arsenal got? We're going to find out in the coming weeks.
Garry Hayes is Bleacher Report's lead Chelsea correspondent and will be following the club from a London base throughout the 2013-14 season. Follow him on Twitter here @garryhayes