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The holders are through, five of five and assured of top spot in Group G with a game to spare. That Manchester City have done all that while being so far from their best, as they were in Tuesday's 3-2 win over RB Leipzig, tends to feel like a shot across the bows for their rivals at home and abroad. If we can do this on our off nights, imagine what we will be like when we hit our groove.

It is a frightening prospect. So, at least for Pep Guardiola, should be a first half that saw them slide into a two goal-deficit as Lois Openda carved through a defense engaged in its worst habits. Erling Haaland and Julian Alvarez swung the contest in the second half, the former striking a late winner to conclude an 18-pass, 10-man move that Leipzig could not answer. In that mood, few teams in Europe can live with them. Better opponents might punish them more severely for lapses that have been a little more frequent of late: that clumsy display against Chelsea, a pair of more toothless displays against Liverpool and Arsenal.

If this weren't the best team on the planet, prohibitive favorites in every competition, this more clumsy display could be brushed off. What their rivals will be looking for, however, is a sign that City can inflict wounds on themselves. This come-from-behind win was exactly that, a reminder that even the kings of Europe are mortal.

City offered a callback to years gone by, a display equal measures dominant and daft. Whenever Leipzig stole the ball back they saw green space in abundance to fly into. The positional diligence of so many in sky blue was found wanting, as was their attitude under pressure. Last season, a City defender would invariably take his time to assess any dangerous situation, waiting to make the optimal intervention. Tuesday, Kyle Walker, Ruben Dias and Manuel Akanji were all guilty of looking for a quick, cavalier way out under pressure. That was enough to nerf their territorial advantage. 

At halftime, every statistic pointed in their favor -- possession, shots, expected goals, field tilt -- except the one that really mattered in the top left corner. Chastened by their 3-1 defeat in Germany and the 8-1 aggregate hammering in the round of 16 earlier this year, RB Leipzig concluded that playing out from the back was more danger than it was worth.

Instead, they were prepared to go direct, sending Openda to chase balls in the channel and beyond. The Belgian is strong, fast and fearless but Akanji should have had the measure of him when goalkeeper Janis Blaswich punted the ball into the space between the center backs. Akanji tried to barge his forward off the ball and flick it to safety. He did nothing with the sort of authority to put Openda off his stride, instead he cruised into the box before bending a shot away from Stefan Ortega.

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This was no freak moment. Carelessness was rife at the Etihad. Passes were not hit with their usual crispness, the press not quite enough to nerve Leipzig when they did play short. Kyle Walker found himself caught upfield when one attack broke down. No great problem, City had two who could deal with Openda when the ball was played to him down the left.

At his best Ruben Dias would let the moment come to him, easing the striker to a less dangerous spot as City bodies scrambled back. Instead, he tried to win the duel in the Leipzig half when he couldn't realistically get near the ball. He fell to the ground. A scrabbling Josko Gvardiol overcommitted too. Both could have learned from Openda's composure as he steadied himself before drilling the ball in at the near post.

Guardiola doesn't seem the sort to lose his rag at the interval but his displeasure was clear for all to see when Dias was replaced by Nathan Ake for the second half. When progress was not immediate in the subsequent, Walker and Jack Grealish were sacrificed for Julian Alvarez and Jeremy Doku. Before those two could even establish themselves in the game the deficit was halved, Leipzig guilty of the same clumsy defending that City had displayed at the same end.

For an instant, Lukas Klostermann lost track of Erling Haaland. Along the line Mohamed Simakan was playing him on. In an instant, number 40 was up, 35 games enough to bring Haaland within three of Kylian Mbappe, four of Mohamed Salah, 10 of Thierry Henry.

Haaland might have set City back on the right course but it was Julian Alvarez who changed the game. With his introduction, the hosts had a player capable of finding space around Leipzig's midfield three. Where he led others followed, Phil Foden dropping between the lines to claim a fizzing Gvardiol pass. His first two touches took him away from Simakan before a low shot rolled through Klostermann's legs.

With 20 minutes to go, it seemed a matter of when, not if, City won. To Leipzig's credit, it took until the dying minutes, for an instant they thought they had won the game when substitute Fabio Carvalho drove in after a give-and-go he had initiated with his backside.

City, however, tend to find a way. Doku and Foden combined along the left. Alvarez found space again and with one touch he rolled the ball into the bottom corner. To overcome a two-goal deficit is surely the mark of champions but the best version of this team would never allow the opposition into this position. Guardiola has a ways to go to get there.