Chelsea will hope this constituted normal service being resumed. A team that had been shaken by its own complacency up at Newcastle United over the weekend recovered its momentum in emphatic fashion, their aggression and industry overcoming Schalke to gain breathing space at the top of the group.

Roman Abramovich visited the home dressing room after the match and discovered the throng in celebratory mood. One more win will secure the section.

This was a reaffirmation of the José Mourinho effect. The manager had been so disgusted by his team's display on Tyneside – and dismayed by Eden Hazard's timekeeping – that he carried through his threat to reshuffle the pack in search of a response, albeit not with 11 changes but six, one of which was enforced, surely stinging the pride of the discarded.

There was validation, too, of the club's lavish summer pursuit of Samuel Eto'o and Willian from Anzhi Makhachkala, with that pair, so rusty upon arrival, enjoying their most productive evening yet in English football.

The veteran Eto'o scored twice and has now registered for four different clubs in a competition he has already won three times, numbers that will make appealing reading. His first goal was pure opportunism, Eto'o charging in to block Timo Hildebrand's clearance and Chelsea's anxiety melted away as the loose ball dribbled into the empty net. By the end they had brought the Germans, so impressive in the opening exchanges, to their knees.

"We recovered the ball and played in an aggressive way, attacking the spaces with two or three players," Mourinho said. "In the end, we won quite comfortably. After the Basel defeat [in the first game] we'd put ourselves in a difficult situation, so it's fantastic that we have qualified after four matches. Oh, we haven't? Well, almost."

A point will be enough to progress and the strength in depth displayed bodes well for the latter stages. Chelsea had been waiting for Eto'o to make a proper mark for them, with the Cameroonian duly exploiting Fernando Torres' absence with an adductor muscle problem to ensure the Spaniard was not missed.

The cheekiness of his first goal conjured up memories of the embarrassment he had heaped, illegally as it should have transpired, on Cardiff City's David Marshall last month. Then the visiting goalkeeper had been bouncing the ball in front of the Shed End. Here, Hildebrand dawdled over a clearance with the ball static just outside the area, the Germany goalkeeper retreating belatedly to muster a runup only for Eto'o to pounce.

Hildebrand duly panicked and his kick thumped against the striker's right leg and trundled into the empty net. Mourinho suggested Chelsea had been well aware of Schalke's propensity to take their time before kickstarting moves from the back, with his manic celebrations with the player on the touchline a reflection of a plan executed perfectly.

"Timo made a mistake, it won't bring him down," said the visitors' crestfallen manager, Jens Keller. "He's 34 and is experienced. He'll be fine."

His team were not. The shambolic concession knocked the stuffing from them, all their early ascendancy undermined in an instant. The Germans might actually have scored three times in the opening eight minutes, so nervy were the home side with memories of the debacle at St James' Park still fresh. Julian Draxler's sidefoot just wide from Atsuto Uchida's pass set the tone, the young Germany international midfielder then marauding from just inside his own half to set up Adam Szalai at his side, only for that shot to drift beyond a post.

Christian Fuchs's wild drive completed a hat-trick of missed opportunities. Mourinho, scowling disapprovingly from his technical area, took most of his frustration out on André Schürrle, his nearest player. This was no way for the winger to celebrate his 23rd birthday.

Yet the mood would improve. Once Schalke were chasing the game, Chelsea eased themselves further ahead on the counter. Petr Cech did wonderfully well to deny Draxler but the home side's response was brutal. Willian, recently called up to the Brazil squad, darted through the centre away from Fuchs and, with Ramires acting as a decoy, his slipped pass for Eto'o left the Schalke back line in disarray. The forward's collection was calm and his finish crisply dispatched across Hildebrand and in off the far post.

There was even time for Demba Ba, a late replacement for Eto'o, to turn and shin in a first goal of the season, with Schalke forlorn and desperate.

"It was a shaky opening but we settled down and started to play from the first goal," John Terry said. "We wanted to respond. We did that. The result puts us back in the driving seat in the group but it was the way we responded that was pleasing – the manager made some changes and the ones left out will be disappointed but those who came in took their chances."