Arsenal boss Arsene Wenger was perplexed by his side’s poor performance against FK Ostersunds during their 2-1 home defeat in the Europa League at the Emirates on Thursday evening.

The Gunners may have progressed 4-2 on aggregate after winning 3-0 in Sweden in the first leg last week but Graham Potter’s impressive side narrowly failed to create one of the biggest shocks in European football history after their victory.

Englishman Potter’s courageous Scandinavians gave the Gunners the shock of their lives after going 2-0 up in North London through an own goal from Calum Chambers on 22 minutes followed by a second by Ken Sema 60 seconds later.

The home side calmed frayed nerves after pulling a goal back through Sead Kolasinac just after half-time to see them through – but it was Potters braves that won the plaudits on a cold night.

Speaking after the match Wenger admitted: “We were not at the races in the first half. We were complacent and not focused.

“We prepared properly and in a serious way but the fact we won 3-0 and have another big game in Sunday [had an influence]...we played against a good side.

“You have seen many upsets like that in the FA Cup. It is better not to talk too much tonight and focus on Sunday.”

When he was asked what Pep Guardiola and Manchester City would make of the result and performance he replied testily: “You should ask them.”

Ostersund boss Potter was magnanimous in defeat after the match and was full of praise for his men as well as Arsenal.

Putting his disappointment to one side he said: “Arsenal is a top team and a top club but we can look back on this tie with pride.

“For a club of our size and stature to complete with a club of this size is great. Arsenal punished us in the first leg but I am so proud overall.

“As an English guy I want Arsenal to do well.

“I’m incredibly proud of the performance. The manner of our performance, the courage of our players...I congratulate Arsenal and hope they go on to win the tournament but I have a great pride in my team.

“To come to Arsenal and take a 2-0 lead is not easy. I congratulate Arsenal for going through. The team they picked was respectful of us. They played a strong team in both games.

“Arsene Wenger said to me afterwards ‘good game’ and I wished him well in the next round.”