London (AFP) – Per Mertesacker has revealed he will go into Arsenal’s FA Cup final against Double-chasing Chelsea without a single minute of reserve-team football following a serious knee injury.

And the German, picked because of a defensive injury crisis, is set to slot into a formation that he admits is entirely unfamiliar to him.

Mertesacker underwent knee reconstruction surgery last year and was not expected to play this season.

But he was thrust into action on the final day of the Premier League campaign, at home to Everton last Sunday, when Gabriel suffered a knee injury of his own at a time when Laurent Koscielny had already been shown the red card that means he is suspended for the final.

As a result, Mertesacker will arrive at Wembley having played just 37 minutes of first team football. And, strange though it sounds, no reserve-team action either.

“I didn’t particularly ask for it,” he said. “I thought when I got a game for the first team it was enough for me, that was my mindset. 

“So before Sunday I didn’t have a proper game, just training sessions. I thought I could compensate with my experience. 

“It felt really good. I didn’t feel like I missed something by playing another game. Even if I would have played two or three months ago it would not have made a difference.”

– ‘Scoring machine’ –

Manager Arsene Wenger has switched from a traditional back four to a three-at-the-back arrangement with wingbacks in the German’s absence. Mertesacker admitted the new system was alien to him.

“With a back three everyone starts from zero, including me — I had never played in a back three, honestly,” he said. 

“When I started as a youngster I played in a back four and that was my position from then on.

“Much of it is small adjustments, and what it comes down to is communication, giving others information so everyone knows what they are doing. It’s more compact in the middle, and sometimes you forget the ball and just defend, allow ourselves to relax a little bit more.

“Without the ball we have to press and just defend the box from the box, but it’s still like a learning curve for us with a back three for those who haven’t played it before.”

Mertesacker, 32, is set to play against Diego Costa for the first time since being sent off for a challenge on the Chelsea striker in league action in January last year.

Wenger was highly critical of Costa’s part in the red card award, claiming he had tried to deceive the referee.

“There is so much the past, I have forgotten about it,” Mertesacker said. “You cannot think about it. That is all I try to do, learn from mistakes.

“He is one of the main threats. He knows what he is doing. Especially in the box, he is a scoring machine. 

“If you talk individually about Chelsea they have played a fantastic season. But there is a lot of responsibility for every one of us to defend.”