PARIS (AFP) - Chelsea booked their passage to the Champions League knockout phase on Tuesday with a 3-0 win over Valencia at Stamford Bridge while an already-qualified Arsenal went down to defeat at Olympiakos. Valencia enjoyed some impressive periods on the ball, but the Spaniards -- who went into the final-day duel level on points with their rivals -- never recovered from a third-minute opening goal from Didier Drogba, who played a starring role in a match which saw the Blues win Group E at Bayer Leverkusen's expense. Daniel Sturridge hit a laser-guided pass to Juan Mata and the former Valencia star fed Drogba, the Ivory Coast striker firing home an unerring left-footed finish. Jordi Alba responded by striking the post for Valencia but Chelsea , knowing they had to go for the three points to ensure further progress, turned the screw again on 22 minutes as a defensive mix-up, coupled with a mazy Drogba run, saw Ramires nip in ahead of Victor Ruiz to score. A neat Drogba finish with 14 minutes remaining wrapped up an ultimately comprehensive victory, with Chelsea emphatically crushing any talk of crisis at the club three days after winning by a similar scoreline at Newcastle. Chelsea , who had made life hard for themselves after squandering leads in their three away matches, won the group by a point with 11 points from their six games after Leverkusen could only draw 1-1 at Belgian makeweights Genk. Drogba said the side had been focused on the job and determined to win. "There was a lot of pressure (but) our attitude was positive," the Ivoirian told Sky Sports. "I think the pressure sometimes can be positive." Coach Andre Villas-Boas praised his men. "They worked very hard for this win - and guess what? We finished top of the group against all odds," he smiled after consigning Valencia to the Europa League. Arsenal meanwhile were able to ring the changes -- nine in all compared with their weekend romp at Wigan -- having already won Group F. But Arsene Wenger's 200th European match in charge ended in a 3-1 loss to Olympiakos, who were two minutes away from joining them in the next round only to be denied by a last-gasp Marseille goal at Dortmund. Algerian forward Rafik Djebbour netted the hosts' opener before substitute 'keeper Vito Mannone -- who came on for the injured Lukasz Fabianski -- completely flunked an attempted clearance as David Fuster made it 2-0. Yossi Benayoun pulled one back on the hour but the Gunners almost conceded again when Mannone missed coming for a loose ball and Francois Modesto headed wide of an open goal before finally making amends with the late third. "I have some regrets," Wenger admitted afterwards, noting his team lacked experience at this level. Didier Deschamps' Marseille joined Arsenal in the hat after the 1993 winners came from 2-0 down in Dortmund to win 3-2 with two goals in the final five minutes and sneak in ahead of Olympiakos by a point with substitute Mathieu Valbuena hitting a brilliant winner. Like Arsenal , Barcelona -- the reigning champions and the team who denied Wenger in the 2006 final -- also sent out a second-string side but they showed their strength in depth in brushing aside BATE Borisov at the Camp Nou. First, 19-year-old Sergi Roberto produced a classy finish for Pep Guardiola's side ten minutes before half-time and then Martin Montoya and a brace, one a penalty, from Pedro Rodriguez, emphasised the huge gulf in class. Barca won Group H at a canter with 16 points while seven-times winners AC Milan, held 2-2 at Czech outfit Plzen, also went through on nine points. But Porto, who won the trophy in 2004 under Jose Mourinho, are out after Zenit St Petersburg held them to a goalless draw in Portugal to go through from Group G.