Bayer Leverkusen manager Sami Hyypia believes that his side lacked the correct mentality against Manchester United in the Champions League on Tuesday.

The Germans were beaten 4-2 by the Premier League champions at Old Trafford in their opening match of Group A thanks to a Wayne Rooney brace and strikes from Robin van Persie and Antonio Valencia.

Hyypia admits that his club lost to the better team and singled out the performance of Rooney for praise.

"Before the game, we talked a lot about the mental aspect of these matches because it's a very important factor in football," Hyypia told reporters.

"I think we were lacking some elements of that today. We have to continue working hard in order to improve in that area. However, you should not forget that we lost to a very good team today.

"It looks so easy the way [Rooney] is playing. He is still scoring goals and he will continue to score them."

Leverkusen travel to Mainz 05 in the Bundesliga on Saturday.