NAPLES, Italy -- Here are three quick thoughts after Manchester City reached the round of 16 in the Champions League with a 4-2 group-stage win at Napoli on Wednesday.
Sergio Aguero became Manchester City's greatest ever goalscorer as Pep Guardiola's side secured a place in the Champions League knockout round with a fantastic win at Serie A leaders Napoli. The striker hit City's third of a 4-2 win as they secured arguably their greatest ever away victory in Europe to make it four winsout of four in Group F.
City made it 14 straight wins in all competitions with another stunning team performance on what was probably their toughest test of the season so far -- particularly at the ultra-intimidating Stadio San Paolo where Napoli had never lost to a Premier League side on five previous occasions.
Maurizio Sarri's side are also unbeaten there this season and their passionate fans were full of expectation after their breathtaking start to the Serie A season. City were growing in confidence, and this was another significant performance and result as Guardiola tries to turn his side into potential European giants.
Napoli dominated the opening half hour and were deservedly ahead after 21 minutes through Lorenzo Insigne. The Italian played a delightful one-two with Dries Mertens, who back-heeled the ball back into the path for Insigne to lift the ball over Ederson.
But City showed they were ready to fight and were back level 10 minutes later when Nicolas Otamendi headed in from Ilkay Gundogan's deep cross after a short corner.
Napoli had been forced to rearrange their back four when Faouzi Ghoulam limped out of the action with the right-footed Elseid Hysaj switching to the left-hand side and the change seemed to affect them.
John Stones nearly put City ahead with a header that smacked the crossbar on 40 minutes but three minutes after the break he was slightly more accurate -- this time a header hit the underside of the bar and bounced just over the line. The goal punctured the hostile atmosphere, however, the Napoli fans were back believing in their side on 62 minutes when they were given a penalty after Leroy Sane tripped Raul Albiol in the box, with Jorghino rolling in the spot kick.
Jose Callejon had a golden chance to put them ahead moments later but Ederson made a fantastic save from a one-on-one before they were caught out by a lightning-quick break from their own corner. Sane sprinted through the home defence and the ball broke for Aguero, who coolly slotted past Pepe Reina.
That seemed to end all hope of a Napoli snatching the victory they needed and City wrapped up the win when Raheem Sterling added a fourth with a neat finish in injury time.
Aguero's 69th-minute strike made him the greatest goalscorer in Manchester City history and it seemed pertinent that he should do it on the night of one of City's greatest night's in Europe.
The striker now has 178 goals for the club to move clear of Eric Brook, whose record stood for 78 years.
Ironically, it wasn't the greatest night for Aguero, who struggled to make an impact in the game. The 29-year-old still looks like he's working his way back to his best form after fracturing a rib in a car crash in September.
He had one opportunity in the 32nd minute with a strike that was deflected off target but he finally broke the record when he cleverly side-footed the ball past Reina after an incisive City break.
Aguero could have beaten the record seven days earlier in the League Cup victory over Wolverhampton Wanderers but that game ended in a stalemate, but it seemed more fitting that he should do it in such a memorable evening for City and at the home of another Argentinian great in Diego Maradona.
Napoli are chasing a first Serie A title since the days of Maradona in 1990, but Wednesday's defeat underlined how difficult it could be for them to mount a challenge in Europe as well.
Sarri's side are six points adrift of second-placed Shakhtar Donetsk and need to beat them in their next fixture at home and hope that City do them a favour by winning in Ukraine.
But the Napoli boss may be best served by switching his attention to their Serie A challenge where they have been so impressive, winning 10 of their opening 11 games to move two points clear at the top. The loss of Ghoulam to injury after half an hour showed that Napoli may not have the depth in the squad to mount a challenge both domestically and in Europe.
Napoli's last game is away to Feyenoord, who have not taken any points from their opening four fixtures and they should expect to at least claim a place in the Europa League. But with Juventus unlikely to give up their Serie A title without a fight, Sarri may well consider switching all his thoughts to ending Napoli's 27-year wait for an Italian title.
Jonathan is ESPN FC's Manchester City correspondent. Follow him on Twitter: @jonnysmiffy.