The sunny climes of City's Florida base appeared to refresh and rejuvenate a side that was so disappointing this season - but on Monday night their Club World Cup hopes fell apart.
The new signings all played a significant part in the tournament and it was evident that Dutchman Tijjani Reijnders will bring much-needed energy and enthusiasm to the midfield.
France international Rayan Cherki got off the mark in the group stages and provided a glorious assist for Phil Foden's extra-time goal against Al-Hilal, but there are major concerns at the other end of the pitch.
While Algerian full-back Rayan Ait-Nouri's attacking ability is undoubted, there are question marks over his defensive capabilities, having been caught out on occasion against the Saudi side.
Matheus Nunes is a midfielder playing at right-back and though City managed to paper over it during the group stages, the square peg in a round hole was glaringly obvious once up against decent opposition.
Sources had not ruled out the signing of a new right-back before the tournament and it remains to be seen whether the club make a move for one.
Guardiola also needs to address the lack of pace in the heart of the defence, with the two central defenders looking particularly sluggish when attempting to chase back the speedy Al-Hilal forwards.
The Spanish boss has made it clear he needs to trim his squad heading into the new season and there may be question marks over the future of England international John Stones, who was the only outfield player not to see any minutes on the trip.
Meanwhile, it remains to be seen whether midfielder Rodri, who missed most of the season through injury, has suffered a setback.
Guardiola said he "complained about his situation" having come on as a second-half substitute before being taken off in extra-time.