Super Eagles forward Alex Iwobi returns to Arsenal's matchday squad for the visit of Middlesbrough after missing out the humiliating defeat to Crystal Palace a week ago but will start from the bench.The Gunners welcome back Laurent Koscielny and Petr Cech in the starting XI as both players passed a late fitness test to make the final cut. Koscielny lines up in the defence alongside Gabriel and Rob Holding as Arsène Wenger has opted to line up with three at the back. There are six changes in total, with Petr Cech starting in goal ahead of Emi Martinez.Alex Oxlade-Chamberlain starts on the right with Nacho Monreal on the left flank. Aaron Ramsey and Granit Xhaka will pair up in central midfield. Olivier Giroud is set to spearhead the attack, supported by Mesut Ozil and Alexis.Arsenal XI: Cech, Gabriel, Koscielny, Holding, Oxlade-Chamberlain, Ramsey, Xhaka, Monreal, Ozil, Alexis, GiroudArsenal subs: Martinez, Bellerin, Gibbs, Coquelin, Elneny, Walcott and IwobiBoro XI: Guzan, Barragan, Ayala, Gibson, Fabio, Clayton, De Roon, Leadbitter, Ramirez, Downing, Negredo.