Germany defender Per Mertesacker admitted he feared for his eyesight after a clash in a Euro 2012 qualifier fractured his eye socket.

Werder Bremen's Mertesacker lasted just 10 minutes of Germany's 6-1 win over Azerbaijan last Tuesday in Cologne after he took an elbow in the face challenging for a high ball.

The blow left him with bleeding around the eye and the 25-year-old centre-back admitted he immediately feared for his eyesight.

"I was afraid on the pitch and remember thinking: 'what has happened, what will happen now?'" Mertesacker told German daily Bild.

"My greatest fear was that something serious had happened to my eye.

"It was as if someone had hit it with their bare hands."

Azerbaijan striker Vagif Dzavadov was the player whose stray elbow caught Mertesacker and the Germany star said he was furious Swedish referee Markus Stroembergsson did not show him a yellow card.

"They have thousands of training courses a year - and then something like this happens," said Mertesacker.

"I don't understand why nothing was done about it."

Mertesacker will be out for at least the next fortnight and will miss several important games for his club.

While his Bundesliga side face Bayern Munich in the German league on Saturday and then against Tottenham Hotspur in the Champions League next Tuesday, Mertesacker, who has 71 caps for Germany, has been told to rest.

Physical activity has been ruled out by doctors for fear of making the injury worse and damaging the delicate tissues around the eye.

"It's pretty difficult, but I have to avoid shocks above all else," he said.

Once the swelling has subsided, a plexiglass mask will be made for Mertesacker to allow him to return to football training, then running and team practice will be introduced gradually.

He is hoping to be fit for the home game against Mainz on September 18.

"Three weeks of rest are the norm, but next week we may know more," he said.

Germany face Turkey in their next Euro 2012 qualifier at Berlin's Olympic Stadium on October 8.