Alexis Sanchez’s wonderful free-kick gave Arsenal the lead against Middlesbrough at the Riverside this season.The Chilean’s goal calmed the nerves of those Arsenal fans fearing a fifth straight defeat away from home in the Premier League. It was hoped that, against a side battling the drop, the Gunners would go on to score one or two more goals to complete a convincing performance.But this is Arsenal we’re talking about. An Arsenal side which for far too long now has lacked backbone and resilience.And so, just five minutes after the restart, it was hardly the biggest surprise when Middlesbrough equalised.Alvaro Negredo tucked the ball beyond Petr Cech following a string of errors from Arsenal’s players.Sanchez first gave the ball away as he attempted a pass. Then Nacho Monreal put up little fight as Stewart Downing cut onto his favoured left foot and swung in a cross.And, not to be outdone by teammates, Laurent Koscielny was caught ball-watching as Stewart’s delivery landed over his head and perfectly into Negredo’s path.Check out the Middlesbrough striker’s goal below.

ArsenalFanTV will have a field day complaining about that one.

Arsenal fans react

In a season filled with frustrating moments, this was yet another. Arsenal fans voiced their anger over Koscielny’s defending on Twitter.

Mesut Ozil grabbed the winner

And to think, Arsene Wenger wanted to see a better defensive performance from his players in the wake of recent defeats to Crystal Palace and West Brom on the road.

"Just to be more solid defensively, we of course have to defend better as a team,” he said prior to kick-off, per the Evening Standard.

"I felt in the last two games away from home we had a lot of the ball and didn't create a lot and were vulnerable defensively, that's all you hate in the game so let's first try to come back with a good defensive stability.”

Luckily for Koscielny, Mesut Ozil popped up to score the winner for Arsenal. The German finished ruthlessly following Aaron Ramsey's knockdown.

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