Ljungberg was was placed in temporary charge following Unai Emery's sacking last week but this past weekend's draw at Norwich was followed up by a poor performance as Brighton secured its first ever away victory against the Gunners.
Adam Webster's second goal of the season gave Graham Potter's side a deserved halftime lead, before Alexandre Lacazette equalized with a looping header five minutes after the break. Arsenal pushed for a winner but instead it was Maupay who turned the ball home in the 80th minute.
The loss leaves Arsenal mired in 10th place after 15 games, 10 points outside the top four.
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