After a run of five straight league wins, Mikel Arteta will be intent on keeping his Arsenal players focused in training ahead of FC Porto. Arteta won’t want to sour the incredible mood around London Colney right now, but he will want to keep feet on the ground, especially with such a big game on the horizon. Arsenal haven’t enjoyed the most fruitful relationship with the Champions League knockout stages in the past, something they’ll want to change. And whilst Porto aren’t having their most successful season domestically, they could still prove a tough stylistic match up for The Gunners. That…