MANCHESTER: Pep Guardiola and Maurizio Sarri are old friends. The managers of Manchester City and Chelsea make a point of enjoying a dinner together every summer. Guardiola may feel he should pay the bill this year: Sarri has received no other favours from City on his debut season in England.

Indeed, events in Manchester have raised questions about how long he may remain as Chelsea manager under the infamously impatient regime of Roman Abramovich.

City’s 6-0 victory lifted them back level on points with Liverpool, ahead of them on goal difference. Sergio Aguero’s hat-trick also provided a devastating warning to Schalke after the confidence and fire-power heading for Gelsenkirchen in the Champions League next week.

City now lead Chelsea 2:-1 in all competitions this season, having also won in the season-opening Community Shield. The evidence from Manchester suggests they are likely to claim a third victory in the League Cup Final on February 24.

Both managers and their sets of players began the day under intense pressure. In City’s case it was to maintain the pressure on Jurgen Klopp’s men while Chelsea needed to regain the winning consistency of last autumn after losing 4:0 to Bournemouth then winning 5:0 against Huddersfield.

City make three changes to the side who beat Everton on Wednesday. Oleksandr Zinchenko returned in defence in place of Nicolas Otamendi, Kevin de Bruyne started in place of David Silva while Leroy Sane was replaced by Raheem Sterling.

Chelsea make two changes with Antonio Rudiger regaining his role in central defence from Andreas Christensen and Pedro replacing Willian in attack in support of the newly-settling partnership of Eden Hazard and Gonzalo Higuain.

Chelsea started positively but their defence fell apart after only four minutes when Raheem Sterling shot City ahead from Bernardo Silva’s right-wing cross. For Chelsea the writing was on the wall. City have never lost in the league on the 35 occasions when Sterling has scored.

Three minutes later and it could have worse. Silva again provided the cross, this time from the left, but all-time club top scorer Sergio Aguero shot wide when it appeared impossible to miss. The Argentinian made amends in the 13th minute with a magnificent goal from 25metres – one of his very few from outside the penalty area.

Five minutes later and Aguero struck again. This was another Chelsea nightmare. David Luiz headed out from a Kevin de Bruyne cross, Ross Barkley headed it back over Luiz towards his own goal where unmarked Aguero twisted to shoot home. Aguero then turned creator as Ilkay Gundogan thumped No4 beyond Kepa.

City keeper Ederson was tested once in the first half by Higuain but it was already a lost cause.

Aguero converted a 55th-minute penalty to equal Alan Shearer’s record of 11 Premier League hat-tricks. It was his 160th goal in 229 appearances for City in all competitions. Sterling claimed his own second goal with 10 minutes left. It was City’s 120th goal in all competitions, far beyond anyone else in the big-five leagues.

​Chelsea’s biggest defeat since 1991 pushed them below Arsenal on goal difference into sixth place.