The Champions League is not supposed to serve up mismatches as resounding as this. Chelsea juggled their first-team options and still strolled to their biggest ever home win in this competition, hardly breaking into a sweat in the process. Life among Europe’s elite is not normally this comfortable.

Genk, the champions of Belgium, chased shadows throughout, their garish pink kit offering them no chance to hide. They will be quaking in their boots at the prospect of meeting these opponents again in a fortnight. For Chelsea, even with their lead at the top of Group E still only a point, the section is already feeling like a breeze.

Even with a selection that reflected Sunday’s forthcoming derby against Queens Park Rangers, Chelsea might have anticipated this saunter. The visitors had arrived in disarray, their confidence brittle and the team severely depleted. Key players from their title-winning side have since been sold, the coach who steered them to the championship, Frank Vercauteren, having departed for Abu Dhabi in August, and other pivotal performers such as David Hubert now cluttering up the treatment room back home. The Argentinean Abel Masuero had made his competitive debut at centre-half on Saturday with the team duly subsiding to a 3-1 defeat at KSC Lokeren. Genk are currently ninth in the 16-team Jupiler League with 13 points. It is a reflection of their regression that they had twice as many points at the same stage last term.

Theirs was a makeshift back-line still, with the midfielder Daniel Tozser an unfamiliar centre-half and his partnership with Masuero fledgling and, with Chelsea pouring at the visitors, utterly exposed. This was no occasion to blood young and inexperienced players, or ask more seasoned performers to operate in unfamiliar roles. Genk may not have had a choice, but neither did they stand a chance. The centre-backs almost contrived to conjure an own goal in the opening four minutes though, with their play tentative and their positioning prone, their evening quickly degenerated from that far from promising start.

The contest was over by the interval, by which time the Belgians’ only real objective was to avoid complete humiliation, though even that felt beyond them. Raul Meireles, conducting Chelsea’s rhythm from a deeper lying position alongside Oriol Romeu, had probed and profited, his speculative attempt from 25 yards eight minutes in having fizzed past a static Laszlo Koteles and into the corner. The attempt was accurate, fiercely struck and well executed, though Khaleem Hyland, nominally this team’s defensive midfield shield, had made little effort to close the Portuguese down.

A first goal for the Londoners since his £12m deadline day move from Liverpool was well merited, with Meireles this side’s creative hub given that Juan Mata loitered among the rested. Yet it was Fernando Torres, restored to the line-up while midway through his domestic suspension, who truly revelled in the inadequacies of his opponents. The Spaniard had not scored a goal in this competition since netting against Chelsea for Liverpool back in April 2009, but that wait – amounting to 875 minutes of football – was cut short swiftly enough here. The Spaniard had already poked an attempt against a post when Meireles and Frank Lampard combined, the latter sliding his pass across the hapless Masuero for Torres to collect. His finish was smartly steered beyond Koteles and, already, the game felt won.

There were vague hints of a riposte from Kevin de Bruyne, a talented young winger who seems destined to move to Chelsea at some stage, but Genk’s clearest route back into the game seemed largely to be David Luiz’s tendency to over-elaborate in possession. The Brazilian remains an eye-catching talent when allowed to pass or maraud forward, but his defensive discipline is a work in progress. There was a booking for a lunge at Jelle Vossen, and rather too much meandering out of the middle for Andre Villas-Boas’ comfort. David Luiz is an eccentric centre-half. Thankfully for Chelsea, Masuero’s deficiencies at the other end influenced the outcome of this occasion rather more.

The Argentinian was not tight enough to Torres midway through the half, the Spaniard guiding a free header wonderfully beyond Koteles from Meireles’ cross with Genk’s back-line having long since disintegrated. Daniel Pudil’s foul on Nicolas Anelka just before the interval earning the left-back a suspension from the return fixture in Belgium in two weeks’ time, almost felt like an attempt to ensure he did not have to endure this runaround all over again. As the Czech contemplated a midweek off in early November, Branislav Ivanovic leapt above Masuero – who did not reappear for the second period – to nod in a fourth from Florent Malouda’s free-kick.

This game had been the subject of an attempted boycott by supporters incensed by a hike on ticket prices. If the official attendance of 38,518 suggested that had failed, those who had stayed away might have cursed missing the turkey shoot. Torres should have completed his hat-trick after meeting Bosingwa’s cross inside the six-yard box, only for Koteles to conjure a staggering save. True to the Hungarian goalkeeper’s dismal luck, Salomon Kalou, on the pitch for barely five minutes, tapped in the rebound. This had long since started to feel cruel.

Champions League 2011-12ChelseaGenkDominic Fifieldguardian.co.uk

• City face Bayern Munich, Villarreal and Napoli in Group A
• Sir Alex Ferguson pleased with Manchester United’s draw

Manchester City’s Champions League debut will mark the moment the club arrive at Europe’s top table and will form the basis of a strong challenge for four trophies this season, executives declared after a tough but navigable draw.

André Villas-Boas – whose Chelsea side will face Valencia, Bayer Leverkusen and the Belgian side Genk in their latest attempt to satisfy Roman Abramovich’s obsession with lifting the trophy – said Roberto Mancini’s side had the “drive and quality” to win it at their first attempt.

City’s football administrator, Brian Marwood, said that trips to Bayern Munich, Villarreal and Napoli would be just reward for fans who had followed the club’s journey from the third tier of English football to the Champions League, fuelled by the millions of Sheikh Mansour and an unprecedented signing spree.

“The football club is making history. It’s the first time it’s ever competed at this level and it’s such an exciting time for everyone connected with the club to be sat in a room with some of the best teams in Europe and the world,” Marwood said. “The ambition is to stay at that level. One thing this club has been over the years is inconsistent and we have to make sure we are coming back here year after year.”

He insisted that the European campaign would not affect domestic form: “Given how we’ve built the squad over the last three years we feel we can have a tilt at four competitions.”

Marwood called City’s a “tough” but “open” group and the Bayern Munich director Karl Hopfner said: “There are four teams from the four best leagues in the world, and it’s the hardest group of all.”

Manchester United, last season’s runners-up, have a comparatively easy draw, including an opening trip to Benfica that will stir memories of the 1968 European Cup final. They also play Basel and the Romanian side Otelul Galati in Group C. “We don’t really know much about Otelul Galati but that’s the beauty of the Champions League, you get fresh teams to play against,” said Sir Alex Ferguson.

David Gill, the Manchester United chief executive, said the draw capped a “good day” in the wake of Ferguson’s rapprochement with the BBC. He welcomed the challenge from their near neighbours, despite now facing more of a battle for the corporate hospitality dollar. “It’s good for Manchester, to have two teams in the Champions League. It’s good for the city. We are pretty confident of doing well again this year, though.”

In 1999, when Manchester United won their second European Cup and completed the treble, City were playing Gillingham in a League One play-off final four days later. Marwood said: “I’d have loved some of our fans to have sat there, the ones who have experienced those wet horrible nights at some of those dark and dank football grounds over the last 15 years.”

Chelsea will face their former midfielder Michael Ballack in their first match, at home to Bayer Leverkusen. In their second, they will travel to Valencia, who they have just paid £26m for Juan Mata.

Villas-Boas said that while he believed City were contenders, “Barcelona are the reference”. But the Chelsea manager said the holders were beatable and that his team could win the competition. “They [Barça] can beat any team in the world, but so could Chelsea and so could Real. If I didn’t believe that, I’d quit the game.”

Asked whether City could win the Champions League, he said: “Why not? They have joined together the best talent in the world this year. It’s something unbelievable. It shows what they want to achieve, and they have a winning coach as well, a coach who won three titles in a row at Inter. I don’t see why they wouldn’t have the drive or the qualities to go all the way through.”

Arsène Wenger will renew hostilities with Marseille first forged in his previous job at Monaco, with Arsenal rewarded for their battling performance against Udinese in the qualifying round with a group that includes Olympiakos and Borussia Dortmund. Robin van Persie, the Arsenal captain, greeted the draw with a tweet featuring a smiley face.

The club’s secretary, David Miles, said: “I’m pleased we don’t have to travel too far, to the eastern European clubs. Arsène will see that as a big bonus.”

Barcelona, aiming to become the first team to retain the trophy since Milan in 1990, were drawn against the Italian side, along with Viktoria Plzen of the Czech Republic and the Belarussian champions Bate Borisov.

Champions League draw in full

Group A: Bayern Munich, Villarreal, Manchester City, Napoli.

Group B: Inter, CSKA Moscow, Lille, Trabzonspor.

Group C: Manchester United, Benfica, FC Basel, Otelul Galati.

Group D: Real Madrid, Lyon, Ajax, Dinamo Zagreb.

Group E: Chelsea, Valencia, Bayer Leverkusen, Genk.

Group F: Arsenal, Marseille, Olympiakos, Borussia Dortmund.

Group G: FC Porto, Shakhtar Donetsk, Zenit St. Petersburg, FC Apoel.

Group H: Barcelona, Milan, FC BATE Borisov, Viktoria Plzen.

Champions League 2011-12Champions LeagueManchester CityManchester UnitedArsenalChelseaOwen Gibsonguardian.co.uk

• André Villas-Boas says Cech will miss up to 4 weeks
• Goalkeeper injured knee during training session

The Chelsea goalkeeper Petr Cech faces up to a month on the sidelines after suffering a medial ligament injury in training.

The 29-year-old Czech Republic international, who played in Chelsea’s opening day 0-0 draw away at Stoke, will miss the Premier League matches against West Brom, Norwich, Sunderland and potentially Manchester United – with the match at Old Trafford taking place on Sunday 18 September.

The Chelsea manager André Villas-Boas said his staff were extremely concerned when they saw Cech falling awkwardly at the end of training on Wednesday.

Villas-Boas said: “It was the end of training, a normal training incident. He fell awkwardly with his weight on top of him. We expected much worse when we saw the incident.”

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