The Gunners were already sweating on the fitness of captain Thomas Vermaelen''s ankle injury before the players left for international duty, where fellow centre-half Laurent Koscielny limped off during France''s defeat to Germany in Paris with a reported calf problem.
Should both men fail to recover in time for the trip to the Stadium of Light, then out-of-favour Sebastien Squillaci or Spanish 20-year-old Ignasi Miquel could have to step in to the heart of the defence alongside Per Mertesacker.
Francis Coquelin is another option, but the defensive-midfielder has missed a couple of matches with a hamstring strain.
Meanwhile, midfielders Tomas Rosicky (virus) and Aaron Ramsey, who returned from Wales camp with a calf injury, are also doubtful for the trip to the north-east.
Forward Gervinho is set to rejoin the squad following Ivory Coast''s elimination from the African Nations Cup, but is expected to be given some recovery time.