Bayern Munich deepened the sense of crisis at Arsenal on Tuesday and took a huge step towards the Champions League quarter-finals with a comprehensive 3-1 away win over the English outfit in their last 16 first leg clash.

Another former European champion Porto also won, inflicting Spanish side Malaga's first defeat of their maiden Champions League campaign with a 1-0 win in Portugal to extend their unbeaten run to 20 matches in all competitions.

Bayern took a firm grip of their match early on with goals from Toni Kroos and Thomas Mueller, and although compatriot Lukas Podolski reduced the deficit, Croatian Mario Mandzukic added a deserved third late on to leave Arsenal staring at an eighth successive season without a trophy.

It will heap even more pressure on their manager Arsene Wenger, who had gone into the match on the back of an FA Cup exit to Championship side Blackburn Rovers and a tetchy performance in the eve-of-match press conference.

However, the esoteric Frenchman was gracious in defeat, accepting that they had been well beaten and that they faced a tough task to overcome the deficit in the second leg.

"I cannot hide from the fact that it will be extremely difficult in the return leg," he said.

"But we just have to play to our best and hope that gives us some confidence.

"We played against a side that had no doubts about itself. We saw that their players are confident, which is not the case with our players but things can turn around rapidly."

His Bayern counterpart Jupp Heynckes praised his side's performance and was especially complimentary about Mandzukic's display.

"We scored two goals really quickly, which made things easier for us," said Heynckes, who guided Bayern to the final last season only to lose to Chelsea on penalties.

"We were really good in the first half. After the break we saw that Arsenal are a good side and we had to work hard. But even under pressure we held our nerve," added the veteran coach, who will be replaced by Pep Guardiola at the helm next season.

Porto just about deserved their victory over a Malaga side that played safe, but despite Joao Moutinho's goal for the hosts, the Spanish side can approach the return leg optimistic of extending their dream run.

Porto's Argentinian playmaker Lucho Gonzalez said that, while the performance was satisfying, a second goal would have given them more to play with.

"Our first objective was to win, the second not to concede a goal," he said.

"We achieved both and we are happy. We played really well and it is a pity that we didn't score a second goal."

Malaga's Chilean coach Manuel Pelligrini said that each person was entitled to their own opinion as to whether they had done well to come away only one goal down.

"Whether it is a good result or not we will see at the end of 180 minutes," he said.

"To lose is never good but losing by just the one goal is the best thing we can take from the game.

"We can still turn the tie around at La Rosaleda. We have demonstrated this year that we can compete with anyone," added Pellegrini.