Always difficult to predict these games. The worry, is that Arsenal will want to recover the points they'll think they lost against West Ham. Liverpool have looked decent without hitting a stride. With Henderson out, the team is certainly weakened, irrespective of whether it will allow Firmino to come in. He's a big game player, and Firmino is still settling.
Liverpool's front six will be very interesting when it is announced. Arsenal's team could be predicted easily right now.