Aaron Ramsey has expressed his frustration with the manner in which Arsenal lost to Borussia Dortmund in the Champions League on Tuesday night.

Robert Lewandowski struck a late winner at the Emirates Stadium to snatch the Bundesliga outfit a 2-1 win in Group F after Olivier Giroud had cancelled out Henrik Mkhitaryan's opener.

"In the second half we were in control of the game then obviously we switched off for 30 seconds," Ramsey told reporters. "We were in their box and then 30 seconds later the ball is in the back of our net. I was obviously disappointed with the way they scored their first goal when I was caught on the ball.

"We were a bit slow to start tonight, but after about 25 minutes we got into the game and got our goal and then second half we took it to them. We were in control of the game and didn't look like we were going to concede but then obviously we did. We switched off for a minute and that's what happens.

"We took 20 minutes to get going and found ourselves 1-0 down by then but we showed good character in getting back into the game. We did well and obviously created a few chances, hit the bar and on another night we may have taken the lead. We have to learn from the way we defended for the second goal. They are a good team and they played well tonight."

Arsenal travel to Crystal Palace in the Premier League on Saturday.