Bremen are willing to sell Mertesacker and value him at around £9m.
But sources in Germany said yesterday that Arsenal could land him for less because they are desperate for cash after failing to qualify for Europe, says the Daily Star.
Arsenal have monitored Mertesacker for some time and their scouts are believed to be slightly concerned about his lack of pace.
But they have told Wenger that 6ft 6in Mertesacker reads of the game well and has great ability in the air.
Wenger will also be pleased to hear that Mertesacker is fancies a switch to the Premier League.
The defender said last week: "It is a good thing to get experience playing abroad. I have said that England excites me."