Arsene Wenger conceded his Arsenal team were second best following a chastening 2-0 UEFA Champions League loss at Borussia Dortmund.

The Bundesliga outfit displayed impressive intensity throughout and goals either side of half-time from strike duo Ciro Immobile and Pierre-Emerick Aubameyang were the least their efforts deserved.

Arsenal brought positives from Saturday's thrilling 2-2 Premier League draw against Manchester City into the Group D clash, but must now reflect on opening their Champions League campaign with a defeat for the first time in 11 years.

"I think that we were not at the requested level tonight and Dortmund deserved their win," Wenger told Sky Sports.

"To concede a goal just before and just after half-time; after that the game was difficult of course.

"Energy-wise they were at a higher level. Why exactly? I think they had a much easier game on Saturday than we had but it is not always scientifically predictable.

"But, despite our very average performance we had plenty of chances - that's a little bit the paradox of the night. We could have been leading the game but they, as well had plenty of chances."

Deadline-day signing Danny Welbeck was culpable of spurning chances immediately before both Dortmund goals, but Wenger praised the England international's overall contribution.

He said: "He was dangerous. He tired in the second half.