Guardiola's critical decision
Manchester City's failing at Newcastle was collective. As Pep Guardiola put it, they forgot to play and their motivation wasn't there.
Any attempt to talk about the form of Kevin De Bruyne or anyone else was directed back to the whole by the manager.
That leaves Guardiola with some tricky decisions to make as he weighs up which players can be trusted to go again and step their game up a level for Arsenal, and which are jaded and need to recharge from the bench.
Sergio Aguero scored inside the first minute at St James', yet was otherwise wasteful in possession; De Bruyne and David Silva both struggled to control the midfield; neither full-back had a night that would make them an automatic pick for Sunday.
There are talented players waiting to step in with Gabriel Jesus, Bernardo Silva, and Ilkay Gundogan all brought on in Tuesday's second half and club record signing Riyad Mahrez an unused substitute.
Yet these last few days of training will have been required for the manager to assess his players and work out whether those that started at Newcastle would benefit more from a show of faith and which need a clear sign to get back into form.
Which Arsenal will turn up?
The common theme for the first part of the season was that City had gotten away lightly by playing Arsenal on the opening day.
Victory at the Emirates should never be sniffed at but with the momentum Unai Emery was building, some detractors of the Blues pointed out that it would only get harder to face this new, post-Wenger Arsenal.
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That theory started to crumble in December when Southampton picked up a 3-2 win over the Gunners and they have struggled for form ever since, including a 5-1 spanking at Anfield and a home defeat to United.
Their win over Chelsea showed their strength and Guardiola praise Alexandre Lacazette and Pierre-Emerick Aubameyang ahead of this fixture, but the concept of a tougher Arsenal this season has taken a bit of a battering in the last few months.
Full-backs could decide the game
This may be an unpopular opinion but Kyle Walker seemed to start the Newcastle game pretty well. All too soon, though, things went down hill and Danilo also chose the worst possible time to have his worst game of the campaign.
Both are experienced players with international pedigree and Walker has already been dropped once for a spell of games when his focus appeared to have gone and it cost the team against Crystal Palace.
There are options at left-back in Fabian Delph, Aleks Zinchenko, and Aymeric Laporte while John Stones can fill in at right-back but none of those solutions are straightforward.
Who the manager picks in those key positions should be revealing.