Graham Potter’s understated revolution at Chelsea is starting to make some serious noise. There is no hint of Thomas Tuchel’s replacement struggling to cope with the big Champions League nights and, while it is not Potter’s style to blow his own trumpet, he could be forgiven for reflecting on how far he has come as he watched his new team cruise to victory at the San Siro. These are moments to cherish for a man who once coached students at Hull University. Potter is operating at a far higher level now and his shrewd coaching has steered Chelsea’s Champions League campaign back on course. They are a settled team once more, balanced with and without the ball, and their new owners will be feeling even more bullish about their decision to fire Tuchel given that the past seven days have involved Chelsea twice swatting Milan aside, even if the Italian champions are entitled to argue that a fourth consecutive win for Potter owed much to their momentum being killed off by Fikayo Tomori’s controversial red card. Perhaps it would have played out differently if Tomori, who must take his share of the blame for a panicky attempt to stop Mason Mount shooting when he was through on goal at 0-0, had been shown more leniency against his old team. Yet the jeers aimed at the German officials was about as fierce as it got from Milan. Chelsea were comfortable, goals from Jorginho and Pierre-Emerick Aubameyang taking them top of Group E, and will qualify for the last-16 if they win at RB Salzburg in a fortnight. It has been an impressive response to taking one point from their first two group games. Confidence was restored by that crushing win over Milan at Stamford Bridge last week and there was no sign of Chelsea being intimidated at this historic old ground. “To come here and win is not straightforward,” Potter said. “We played well.” Chelsea, who were still without the injured N’Golo Kanté, played with poise. Potter shuffled the pack once again, dropping Ruben Loftus-Cheek and going for the technical duo of Jorginho and Mateo Kovacic in midfield. The plan, to silence the din by controlling the tempo, was effective. Chelsea exploited the space behind Milan, who toiled without Simon Kjær and Davide Calabria in defence, and soon gave notice of their threat, Reece James and Mount linking up and Raheem Sterling causing problems before the pivotal moment arrived in the 18th minute. Inevitably it was James who prised Milan apart, curving a pass through to Mount. There was too much room for Chelsea’s irrepressible right wing-back, who was not flustered by the challenge of marking Rafael Leão, and questions had to be asked of Theo Hernández’s insistence on drifting into midfield. The left-back failed to engage James and alarm spread when Mount darted through. Nonetheless there was outrage when Daniel Siebert pointed to the spot, judging that Tomori had deliberately denied an obvious goalscoring opportunity. A penalty and a red? The punishment felt severe given that the contact looked minimal as Tomori grappled with his former Chelsea academy teammate, even if the Milan defender’s clumsiness prevented Mount from getting a clear shot away, but the red card was instant. “I don’t believe it was the referee’s best night,” Stefano Pioli said. “I asked whether VAR was working properly.” Tomori, whose second consecutive shocker against his old club could hurt his chances of making England’s World Cup squad, could not rely on VAR. It was galling for Milan, who have slipped to third in the group. Their protests were furious and one fan even tried to put Jorginho off by shining a laser pen in the midfielder’s eyes before his penalty. No matter. Jorginho did not blink before sending Ciprian Tatarusanu the wrong way. Milan were incandescent. They continued to gripe at the referee, who infuriated them with a flurry of bookings, and almost used their sense of injustice to equalise. Brahim Díaz’s cross caught Chelsea napping, but Olivier Giroud headed wide from close range. Chelsea stirred. They pushed again, moving Milan around with a long passing sequence, Kovacic quickening the pace finding Mount. A clever flick opened Milan up and Aubameyang, pushing Sterling aside, drove home his third goal for Chelsea. The game was dead. With Ben Chilwell driving down the left, there was a dynamism to Chelsea. Mount saw a shot pushed away before making way for Conor Gallagher at half-time. Aubameyang went close, while at the other end there was little to concern Trevoh Chalobah, Kalidou Koulibaly and Thiago Silva, who excelled on his return to the San Siro. Weighed down by injuries, Milan ran out of steam. The only concern for Potter was seeing James limp off with a knee problem. Chelsea will not want to be without him for long, but otherwise the mood is good.