Watford went into this game with no recognised centre-backs and a dearth of defensive alternatives, so though the nature of this defeat was painful to watch, it came as no surprise. The visitors could have had double figures had they been minded to get out of second gear, as Watford were as hapless as they were ragged.
Despite Heurelho Gomes' receiving treatment for around five minutes, the officials decided to play a just a single minute of injury time at the end of the match. On afternoons such as this, it's important to be thankful for small mercies.
Watford's injury crisis reached extraordinary heights ahead of this game, and big questions must be asked about how this was allowed to happen. It meant they staggered into a game against one of the best teams in Europe completely ill-equipped, and it mustn't be allowed to happen again.
3 (out of 10) -- Walter Mazzarri delivered a final parting shot to the talismanic Troy Deeney by leaving him on the bench and caused uproar by naming a second goalkeeper on the subs bench after Adrian Mariappa's late withdrawal. Was greeted by chants of "off, off, off!" by the home supporters when spoken to by the referee. A grim ending to his brief Watford career.
Player ratings (1-10, with 10 the best. Players introduced after 70 minutes get no rating)
GK Heurelho Gomes, 6 -- Left exposed by the makeshift defence in front of him on far too many occasions, and but for a number of excellent saves -- including a couple at close range from Sergio Aguero -- the score would have been far worse.
DF Brandon Mason, 7 -- A last-minute replacement for the injured Adrian Mariappa, youth team graduate Mason turned in a good display under the circumstances. Put Gabriel Jesus into the advertising hoardings after half an hour, showing that he wasn't afraid to mix it up with his illustrious opponents.
DF Jose Holebas, 5 -- Played in an unfamiliar centre-back role, Holebas looked understandably unsure of himself and was never comfortable. Disappointed many by not picking up a record-breaking 15th yellow card of the season.
DF Valon Behrami, 5 -- Another player faced with an afternoon in an utterly foreign position, and it showed. Battled gamely as a makeshift centre-back but was no match for man City's marauding forwards.
DF Daryl Janmaat, 5 -- Was left for dead by Leroy Sane, who then crossed for Aguero to tap home. Injured himself trying to stop the German and was replaced by Andrew Eleftheriou after 40 minutes.
MF Tom Cleverley, 5 -- Was unable to stop a rampant Manchester City and was totally overrun in the midfield. Cleverley was an important signing for Watford in January, but after a run of solid showings, he has tailed off in recent weeks.
MF Abdoulaye Doucoure, 5 -- Slipped at a critical time and conceded possession to Kevin De Bruyne, who capitalised by playing in Aguero, who scored with ease. A poor afternoon for the Frenchman.
MF Etienne Capoue, 5 -- After a positive start, Capoue soon found himself struggling to influence the game with Manchester City running riot.
MF Nordin Amrabat, 5 -- Amrabat has struggled since his return from injury and was unable to turn the tide with Watford constantly on the back foot. No attacking threat of note; another disappointing afternoon.
MF M'Baye Niang, 3 -- After going close with an early effort, Niang's only other contribution was to rescue a small bird that came to rest on the Vicarage Road turf.
FW Stefano Okaka, 6 -- On a day when it was easy to give up, Okaka kept going, despite being visibly upset by some of the referee's decisions. Dithered when well-placed early on, but he showed enough to suggest that he could be a valuable member of the Watford squad for next term.
DF Andrew Eleftheriou, 6 -- Making his debut as a replacement for the injured Janmaat, the 19-year-old was solid and impressive in very difficult circumstances.
FW Troy Deeney, 5 -- A quiet half-hour after being brought on to replace Nordin Amrabat. As expected, received precious little service and was unable to carve anything out for himself.
MF Dion Pereira, NR -- Replaced the woeful Niang with 15 minutes to go. Another youth team graduate, Pereira showed a few nice touches in his second outing for the first team.