Mesut Ozil missed a chance to put Arsenal two goals ahead. (AFP/Getty Images)

Arsene Wenger admits Mesut Ozil was ‘guilty’ of failing to secure victory for Arsenal in their 2-1 defeat to Watford on Saturday.

Per Mertesacker gave the Gunners a first-half lead but a controversial penalty award allowed Troy Deeney to equalise from the spot.

Tom Cleverley struck in injury time to secure the win for Watford, but when Arsenal were a goal ahead, Ozil missed a one-on-one chance by firing hit shot straight at Heurelho Gomes.

And Wenger admits Arsenal’s lack of killer instinct in front of goal was one key reason for their defeat at Vicarage Road.

‘I’m not so happy with our overall level in the second half. Our level dropped in the second half,’ said Wenger.

Ozil has been blamed for Arsenal’s defeat. (Reuters)

‘We missed many chances to kill the game, [goal] number two, number three should have been scored.

‘If you look at the game today, with a bit more killing instinct in front of goal, despite that, we should have won the game.

Tom Cleverley scored the winner in injury time (Reuters)

‘That’s where we are guilty.

‘After that, the decision on the penalty we can have no impact on that at all.

‘Not everyone is at the same level physically, but I feel we should have won the game.’

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