This was a curious Manchester City display studded with lax marking and concentration. Pep Guardiola’s side ended by returning an 18th unbeaten group game – 14 of them victories – but he will surely upbraid his charges for the slipshod fare they produced. With Paris Saint-German up next, City cannot afford a repeat against Lionel Messi, Kylian Mbappé, Neymar and co, who will surely watch the film of this and smell blood. Guardiola’s men were able to react each time they conceded but are bound to find it trickier against Mauricio Pochettino’s aristocrats. Still, PSG could only draw at Club Brugge and so last season’s losing finalists already top Group A by two points: this is what can happen when a team is slightly below par yet its sole summer addition is the £100m Jack Grealish, who decorated the contest with a sublime goal and assist. “Leipzig never give up,” said Guardiola. “They play all or nothing. You never had the feeling it’s over. We scored a few minutes after they scored [a few times] and it helped us a lot.” From a match-day squad missing the unfit John Stones and Aymeric Laporte, Guardiola’s centre-back pairing was Nathan Aké and Rúben Dias, with Ferran Torres again the striker, and Kevin De Bruyne, back from injury, chief orchestrator. An initial foray had De Bruyne and Torres interlinking before the former’s cross was gathered by Peter Gulacsi. Here the Spaniard matched the Belgian’s quickness of thought in an instant return pass that took De Bruyne by surprise and boded well for City. So, too, was Grealish’s opening contribution as a Champions League debutant, the reverse flip into Torres oozing guile. It had the No 21 racing clear before being flagged offside. Leipzig were already in a wrestle for decent ball and territory. A Dani Olmo ballooned shot was the best they could conjure, as City took the lead. This was presaged by a Riyad Mahrez ball floated over from the right. It was cleared for a corner – by Nordi Mukiele – which Grealish pinged in and Aké rose to beat two defenders and Gulacsi with a powerhouse header. Guardiola limited his celebration to a soft fist pump but a lead inside 20 minutes will have delighted. So, too, the hunger to rove forward again, Mahrez ghosting into position to pull the trigger, this time on a curving effort that flew wide. Grealish’s next contributions were a hail Mary of a corner and the drawing of a foul by an already frustrated Christopher Nkunku. The emotion was about to permeate all of Leipzig when a hapless Mukiele headed De Bruyne’s skidding delivery past Gulacsi for City’s second. To characterise mildly: here was the very last thing the Germans needed and a serious trouncing seemed possible. Only an element usually scarce under Guardiola might allow them back in to the contest – complacency from their hosts. Surprisingly there was precisely this. As the break neared Olmo was allowed to pass left, Emil Forsberg lifted the cross in, Mukiele headed back to Nkunku and he beat Ederson. City, though, ended the half in near total control. A Torres header hit Lukas Klostermann’s upper arm and after VAR ordered Serdar Gozubuyuk to consult the monitor the referee awarded the penalty. Mahrez smashed in for a 3-1 lead and the visitors were back as remote contenders to take anything home. Moments into the second half calamity nearly befell Gulacsi when careering along the turf as Torres bore down, the keeper finally managing to regain balance and save a weak shot. Torres would soon rue this because by 50 minutes Nkunku had a second: in trying to make a tackle De Bruyne tripped over Gozubuyuk and thus Olmo could receive, then chip between Dias and Aké too easily, for Nkunku to score. This was alarming defending and had Jesse Marsch believing his side might actually prosper. Who could blame him? City had conceded two loose finishes and there was a whiff of an upset. Grealish, though, had another idea and it was to illustrate why his price was in seven figures. After collecting on the left, a shoulder dip left Tyler Adams looking like a statue, before the wide man accelerated on and curled sweetly in to make it 4-2. “When I’m in that position, running into the area I’d back myself against anyone to have a go and it paid off,” he said. Still, Guardiola’s emotion was writ large when meting out an unadulterated rollicking to Mahrez that the Algerian had no choice but to accept. City also had to swallow Nkunku clinching a hat-trick, hammering in Yussuf Poulsen’s pass, to leave Guardiola despairing. Yet this ding-dong spectacle had an eighth strike two minutes later when João Cancelo’s piledriver made it 5-3. An incident-rich evening moved on to Angeliño, once of this parish, receiving a second yellow so Leipzig were a player light. And, by the end, the substitute Gabriel Jesus had made the margin emphatic. “The quality of the players was better today and that’s why we won,” said Guardiola, for whom this was a 300th match in charge.