German media have reported Mertesacker could be close to a transfer to Arsenal, who were crushed 8-2 by Manchester United on Sunday, but Werder have refused to comment.
"Last night I told the player I am giving you a free day and I expect he will come back this evening. I know there was a specific offer from a club," Low told reporters as his side prepared for Friday's Euro 2012 qualifier against Austria.
The Germany coach refused to disclose which team Mertesacker was negotiating with.
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