Unai Emery harbours severe concerns over four of the defenders he has inherited from Arsene Wenger.
The former PSG and Sevilla coach has set about rebuilding Arsenals rearguard this summer with the signings of Germany international goalkeeper Bernd Leno, experienced right-back Stephan Lichtsteiner and former Borussia Dortmund centre-half Sokratis Papastathopoulos.
Arsenal finished sixth last season, winning only once away from home following the turn of the year and conceded 51 goals in total.
According to The Sun, Wengers successor fears Shkodran Mustafi is not up to the job, while he is also said to fear the likes of Calum Chambers, Rob Holding and Konstantinos Mavropanos are not yet ready for regular first team football.
Chambers, who recently signed a new long-term deal, is reportedly on the verge of joining newly promoted Fulham on a season-long loan with Croatia World Cup star Domagoj Vida having been identified as a potential replacement.
The physically imposing Vida joined Besiktas from Dynamo Kiev for £8m January and the Turkish club have rejected a £13.5m bid from Liverpool already this summer.
Having invested heavily this summer and last January, when Mesut Ozil signed a new deal following the arrivals of Pierre-Emerick Aubameyang and Henrikh Mkhitaryan, Arsenal must sell before they can submit a tempting offer for Vida.
Danny Welbeck is expected to leave before the deadline, while Aaron Ramsey could yet raise up to £30m if he fails to agree an extension to his contract which is due to expire next summer.
More: Arsenal transfer news