With the Blues leading through a Pedro effort, the Gabon international shot high a clear chance from Hector Bellerin's cutback in the 19th minute.
53 seconds later, opposite number Alvaro Morata doubled Chelsea's lead.
Aubameyang has, however, admitted to his fault and promised to get better.
After the game, he tweeted: "Today I missed; tomorrow Must Be better!"
Today i missed tomorrow Must Be better !! — Aubameyang P-E (@Aubameyang7) August 18, 2018
Tomorrow for Aubameyang is next Saturday as Arsenal test West Ham United for size, and the Gabon international will hope to have his scoring boots on.