Gunners boss Arsene Wenger has decided to rotate his side heavily going into the Reading clash. Third choice keeper Martinez will start in goal while Germany international of Turkish origin Mesut Ozil, Alexis Sanchez, Santi Cazorla, Theo Walcott and Mustafi have all been dropped from the squad.
Wenger has decided to include Olivier Giroud on the bench after returning from injury but Aaron Ramsey will not feature tonight as he has not recovered in time and Granit Xhaka is suspended.
The North London outfit will have a few familiar faces as Elneny, Oxlade Chamberlain, Lucas Perez and Iwobi will all start.
Arsenal have won all 13 games they have played against Reading and will progress past the fourth round with a victory tonight.
Arsenal confirmed XI: Martinez, Jenkinson, Holding, Gabriel, Gibbs, Elneny, Maitland-Niles, Ox, Jeff, Iwobi, Lucas
Reading confirmed XI: Al-Habsi (c), Watson, Obita, L.Moore, Blackett, Kelly, Van den Berg, Evans, McCleary, Harriott, Samuel.