So, derby day, football's natural reality check, soon took the wind from Arsenal's sails.
Arsene Wenger's side were wonderfully fluent in a five-goal mauling against Everton last week it was tempting to believe a significant corner had been turned.
With Pierre-Emerick Aubameyang's electric pace up front and Henrikh Mkhitaryan's vision added to the flair of Mesut Ozil, they were a destructive force.
Wenger, it must be said, was not getting carried away. 'Let's wait,' said the manager, with a nod to Tottenham.