Wenger was upset by PSV's tactics

"We had a decent first half and created chances to be in front and we could not do it," said the Gunners boss.

"What happened in the second half is difficult to say. We dropped our level of cohesion, our passing and fluency went. We created barely anything.

"We could have been punished more. We looked a little bit out of rhythm."

News conference: Arsenal boss Arsene Wenger

Wenger was unhappy with what he considered negative tactics from the home side.

"They started the game to play for a 0-0. After they scored the goal, they defended even more but somebody needs to play," he added.

However, the Arsenal boss remains confident can recover in the second leg at the Emirates Stadium on 7 March.

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"From tonight I feel we are in a tricky situation because we have to score two without conceding," he said.

"But from the game I have seen tonight, we have enough confidence and belief that we can achieve that."

PSV manager Ronald Koeman hailed his side for producing a "fantastic" win.

"I am very proud of my team and we got the best and deserved result - especially looking at the second half," he said.

"As the match went on, we put more pressure on them and were more compact during the later stages.

"We are in a fantastic position, and if we play the same level in the second half when we go to London then we have a chance."

And the PSV coach denied that his side had been negative during the first half.

"I do not see that as something negative - we had many injuries and did what we could," he said.