Reading haven't won in their last six I believe, so if they manage it today people everywhere will lose their heads. I can't see anything other than a comfortable Arsenal win, probably 2-0 or 3-0, especially with Nathan Ake and Kwesi Appiah cup-tied for Reading.
Chalobah and Mackie are both available, which offers them some hope at least.
Mackie, in particular, is a bulldog centre-forward. He's not the quickest forward but works tirelessly to exploit the space between the full-back and the centre-half.