Alex Iwobi capped 36 times by Nigeria, scored 15 goals in 149 appearances for Arsenal after making his first-team debut in 2015.
Arsenal must now turn the tie around in the second leg at the Emirates Stadium next Thursday if they are to progress any further in the Europa League.
Esha Gupta was heavily criticised after she posted screenshots of a racist exchange about Arsenal winger Alex Iwobi between herself and a friend.
Apart from Pierre-Emerick Aubameyang, substitute Alex Iwobi scored the third goal for Arsenal while Ashley Barnes scored the lone goal for Burnley.
Unai Emery has been busy in the transfer market in his first weeks in charge.