Arsenal's Santi Cazorla is a doubt after taking a kick against Ludogorets in midweek, while Granit Xhaka (suspended) and Aaron Ramsey (hamstring) are sidelined. The match comes too soon for Olivier Giroud (toe).
Arsenal have won only one of their last six Premier League fixtures against Middlesbrough (D4 L1).
Arsenal have won six of their last eight home matches against Boro in the Premier League (D2).
This match is on the same day as Arsene Wenger's 67th birthday. He has won his two previous Premier League fixtures on his birthday, 1-0 v Man City in 2005 and 4-0 v Reading in 2006.
The Gunners have scored one, two, three, four, five, six and seven goals in Premier League matches against Middlesbrough – one of four clubs to do so against another in the PL (also Chelsea v Sunderland, Everton v Sunderland and Manchester City v Norwich City).
Arsene Wenger: "We live in a jungle where everybody wants to eat you and you have to survive by keeping your vigilance. Every day you have to fight again to survive."
Aitor Karanka: "Arsenal have their own style, but we have to think about ourselves and play in our way."