Deadline day left both benches looking like different clubs. Arsenal made a late move for Fofana out of Lyon while Martinelli packed for the Saudi Pro League, and Chelsea kept doing what Chelsea has done all summer: spend. Now both sides have to debut the new-look rosters against each other, at the Emirates, with none of the usual preseason cushion to sort out who fits where.
That is the part that makes 2.5 goals interesting. New signings pressing to make a first impression can mean chaos in behind, unfamiliar shapes, a back line still learning each other's names. It can also mean nerves, caution, two managers happy to see how the pieces move before letting the game open up. Fofana slotting into a new system and Chelsea's rebuilt spine facing real opposition for the first time both cut either way.
Nobody knows yet what either roster actually looks like under pressure. That is exactly the bet on the table: over or under 2.5 goals when the ink is barely dry.