Fine margins. It has become a much-used phrase in sport to describe the narrowness between success and failure. How close it can be. But how much of a difference they can make.
Mikel Arteta was at it last week when he talked about the tiny margin between Arsenal and Paris St-Germain in the first leg of the Champions League semi-final. PSG take a 1-0 lead to Paris, but the gap between the two sides appeared greater on the night.
Now Arsenal are in Paris for the return game and it comes down to this: if they can turn it around and reach the Champions League final, then it will be another season of progress.