A goal from Ollie Watkins condemned us to a second straight defeat in the Premier League.
The Aston Villa striker scored with the help of a deflection off Rob Holding as debutant Mat Ryan was beaten in the second minute.
Ryan made some fine saves after that and we fought hard for an equaliser with Granit Xhaka bringing the best out of former Gunner Emi Martinez.
Substitute Martin Odegaard had our clearest opportunity but he fired over the crossbar from a great position.
You can watch a short highlights clip of the game by clicking on the video above.