Koscielny missed Wednesday's defeat against Swansea with a calf problem and will not recover in time to face Spurs while Cech picked up what appeared to be a hamstring injury in stoppage time against the Swans.
The former Chelsea goalkeeper went forward for a corner in the dying moments of the defeat to Francesco Guidolin's side and it is then that he seemingly suffered a hamstring pull that will keep him out of a potentially season-defining game for the Gunners.
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"He will not play on Saturday. I trust completely Ospina and I have no problem with that.
"It’s a muscle problem, I don’t know how long he will be out. Koscielny is also calf and he will be out too."
Defeat to Swansea on Wednesday means Wenger's side remain in third place in the table, three behind Spurs in second and six off current leaders Leicester City, who were held by West Brom on Tuesday night.