The Gunners have already been without Gabriel, Riccardo Calafiori and Oleksandr Zinchenko, who missed Sunday’s 1-1 draw at Fulham and were absent from training on Tuesday.
Mikel Arteta is set to provide an update on Timber and Partey at a press conference on Tuesday afternoon.
But if both players are also sidelined then Arsenal would be missing six senior defenders, plus Partey who can play at right-back.
Timber completed 90 minutes in Sunday’s 1-1 draw at Fulham
Arsenal FC via Getty Images
Calafiori, Gabriel and Zinchenko all missed Saturday’s 1-1 draw at Fulham and Ben White and Takehiro Tomiyasu are also out.
The Gunners face Monaco at Emirates Stadium on Wednesday.
Calafiori and Gabriel have been absent for the past two games after both coming off early in the win at West Ham on November 30.
Gabriel was forced off at half-time in that game after struggling with an issue he picked up in the game before that at Sporting.
The defender was taken off for the final minutes of that win in Lisbon and Mikel Arteta said it was a reoccurrence of that issue that had forced Gabriel off against West Ham.
Calafiori was substituted just before the hour mark in that game and has not played for Arsenal since then.
The Italian has struggled for fitness since joining the Gunners in the summer and recently returned from a knee injury.
In his absence, Zinchenko was handed a start against Manchester United last Wednesday and helped Arsenal keep a clean sheet in a 2-0 win.
But the Ukrainian was taken off with just under 20 minutes to go and then left out of the squad against Fulham.
Arsenal have been hit hard by injuries at the back all season and they were without five defenders at Craven Cottage.
As well as Calafiori, Gabriel and Zinchenko, the Gunners were also without Ben White and Takehiro Tomiyasu.
Both White and Tomiyasu are out with knee injuries and are not expected to return to action until some point in the new year.
Arsenal’s issues at the back have been eased by the return to fitness of left-backs Kieran Tierney and Myles Lewis-Skelly, who were both on the bench last weekend.
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