Arsenal centre-back set for Bundesliga return
The German international joined the Gunners at the beginning of last season but has been an inconsistent performer during his time at the Emirates.
Mertesacker has appeared in 24 out of 28 Premier League games for Arsenal this season. He also scored in both the North London derby fixtures. However, with Arsene Wenger looking for new defending options, the 28-year-old has been linked with a move to former club Hannover.
He spent 11 years at Hannover before moving to Werder Bremen in 2006.
Wenger may let go of the player in order to make way for younger reinforcements but he would not accept anything lesser than £8m for the experienced defender.