Arsenal were beaten by Manchester United at the start of December. (Reuters)

Arsene Wenger admits his Arsenal players are still upset over their defeat to Manchester United two weeks ago.

Jose Mourinho’s side secured a 3-1 victory at the Emirates Stadium on December 2 but were heavily reliant on a world-class display from David De Gea to keep Arsenal at bay.

Since the defeat, Arsenal have been held by Southampton and West Ham, and have slipped to seventh in the Premier League table.

And Wenger concedes the loss to Mourinho’s men has had a lasting impact on his side.

David de Gea makes a save
David De Gea was in superb form for Manchester United. (Getty Images)
Arsene Wenger admits the defeat was ‘difficult to swallow’. (AFP/Getty Images)

‘Yes, it still plays on their mind, you have to get that out of their system,’ said the Frenchman.

‘When you had so many chances we had and you come out with nothing it’s difficult to swallow and it takes a little while.

‘The best way is to put that behind us and focus on the quality of our game.’