McKenna accepts they go to Arsenal as rank underdogs.
But he also says: “I think we need to show the right mentality, first of all, in the game,” he said. “I think it's a chance to show our togetherness, our spirit and our resilience.
“We're going to have to show a real mental strength. Our organisation is going to have to be really, really good and we're going to have to show bravery at different moments in the game as well to take them on in the way that we want to at different phases of the game.
“For me, it's about the mental characteristics that we're going to have to show in this game. That's what we spoke about this morning and that's what we'll try to show on Friday night.”
After their hammering by Newcastle, McKenna also said: “Obviously, when you lose a home game and in the manner that we didn't want to on Saturday, in some ways going away to Arsenal is a really difficult game to have next.
“But in another way, I think it's a challenge for us to go and take on because the characteristics that we're going to have to show are really, really clear.
“And it's up to us to go and show them now as a group on Friday night. I think it's a challenge that we're looking forward to and it's one that we have to rise to as a group together, the players all together with the staff, and with the supporters, and go there and take it head on, try and give a really good account of ourselves and try and get some points.”