Defeat for Dortmund, Schalke

Ahead of the game on Wednesday evening, Dortmund coach Jürgen Klopp had likened Arsenal's style to that of a classical orchestra, while comparing his own side to a heavy metal outfit.

Klopp's opposite number Arsene Wenger, in turn, had promised a grand symphony. The reality didn't really fit the billing.

Through much of the first half, though fairly defensively competent, neither team looked on-key when it came to attack.

Arsenal's German defender Per Mertesacker was largely successful containing in-form Polish striker Robert Lewandowski, who Wenger had singled out as a major threat before the game.

The home side's best chance of the first half came on 37 minutes when Jakub Błaszczykowski found Henrikh Mkhitaryan in front of goal. Despite having a fair amount of time and space, the Armenian put the ball wide.

Dortmund started the second with a little more impetus. However, it was Arsenal who snatched the lead on 62 minutes, taking advantage of a bright spell as Mesut Özil crossed in to Olivier Giroud. He nodded the ball on to in-form Aaron Ramsey, who guided past keeper Roman Weidenfeller with his head.

The game opened up a little although, once they had their noses in front, the Gunners were able to defend stoutly enough. They might even have finished with another, but the final result of 1-0 was probably fair.

It wasn't a great Wednesday for Dortmund. Earlier on, Lewandowski announced that he would be leaving the club at the end of the season when his contract expires. While the Pole gave nothing away about his destination, speculation remains rife that the 25-year-old is Bayern Munich bound.

Klopp stays upbeat

The game also saw coach Klopp returning to the bench after a two-match European suspension. He remained optimistic about the side's chances of progressing. Dortmund are third in Group F with six points, trailing both Arsenal and Napoli, who each have nine.

"We created much more today up front and we started well in the second half," said Klopp. "But they scored with their first chance of the match and we could not come back. This defeat could have been avoided."

Schalke, meanwhile, were hoping to capitalize on the bad vibes lingering at Stamford Bridge after Chelsea's shock 2-0 weekend defeat to Newcastle United. However, as far as musical analogies are concerned, it was to be very much a case of the blues for the Germans.

Schalke were looking for revenge after losing 3-0 at home to the Londoners in their previous Group E meeting.

Indeed, they came out firing on all cylinders, asking some early questions of the Europa League champions. However, Chelsea soon began to shore up their defense and take hold of midfield, without creating so much in the way of chances.

It was only a bizarre occurrence in the 31st minute that made the difference between the two sides, when Thomas Hildebrand dithered - not for the first time - with his goal kick. Chelsea's Samuel Eto'o saw his chance and pounced to rob the keeper and put the ball in the net.

Eto'o doubled his tally nine minutes into the second half after Brazilian Willian drew the defense and slipped the ball to the Cameroonian - who planted it firmly into the net.

Ba composes the finale

A good night for the Blues from London was capped in the 83rd minute when substitute Demba Ba volleyed on the turn, connecting with a ball from over the top from fellow sub Frank Lampard to hook in the goal.

Schalke are now second in Group E, on six points - three below Chelsea. Coach Jens Keller was philosophical in the face of defeat. "The result was not so good for us, but it's still in our own hands and we still have a good chance to qualify, so everything is still open," he said.

On Tuesday, Bayern Munich ensured they would reach the knockout stage of the Champions League with two games to spare, courtesy of a lone goal from Mario Mandzukic in a 1-0 Group D away win against Viktoria Plzen.

Meanwhile, Bayer Leverkusen remained on course to progress in the competition when they ground out a 0-0 away draw to Ukrainian side Shakhtar Donetsk. That result kept them second in Group A.