Mertesacker is definitely out of Saturday's Bundesliga game with Bayern Munich after being injured in a Euro 2012 qualifier on Tuesday and is rated doubtful for the European meeting with Spurs a few days later.
The Germany international clashed with Azerbaijan's Vagif Dzhavadov in Germany's 6-1 win on Tuesday and had to be taken off in the 11th minute before X-rays revealed a broken eye socket.
"He will surely miss Saturday's match as well as Tuesday's game against Tottenham Hotspur," coach Thomas Schaaf told reporters after further medical tests were completed on Wednesday.
"We will have to wait and see what will happen after that. This is not a good situation for us because apart from (defender) Naldo we are now missing a second central defender."
Spurs begin their Champions League quest in Bremen next week having come though their qualifying tie with Young Boys of Berne over two legs.
Peter Crouch's hat-trick at White Hart Lane helped seal a 6-3 aggregate victory, after Harry Redknapp's men had lost the first leg 3-2 having been 3-0 down after 30 minutes.
New signing Rafael van der Vaart could feature for Tottenham Hotspur having joined from Real Madrid just minutes before the transfer window slammed shut on deadline day.
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