Arsene Wenger labelled Arsenal's heavy defeat to Bayern Munich as a 'nightmare'.

The Gunners conceded early to Arjen Robben but went into the break at 1-1 after Alexis Sanchez equalised on the half-hour mark.

However, Arsenal let in four goals in the second half to capitulate massively at the Allianz Arena in what was a disastrous night for Wenger and his men.

"The real problems we faced came after the third goal because we lost our organisation and we looked mentally jaded," said the Frenchman.

"We looked vulnerable from that moment onwards and the last 25 minutes were a nightmare for us because we had no response.

"The two goals (second and third) were difficult to swallow - 53 and 56 minutes.

"We have to analyse that but it looked from the outside that we lost our organisation.

"Not only did we lose our centre-back (Laureny Koscielny to injury) but after the third goal it was a combination of mental and organisational because before that we controlled them quite well."

Wenger added: "The fact is we have to cope with the result.

"No matter what we say now it will be turned in a way that is detrimental to us because we have had an extremely bad result."