Mikel Arteta has "got problems" with Hector Bellerin and must switch to a back four, according to ex-Arsenal captain Tony Adams.
Arsenal suffered their second loss of the new season at the hands of Manchester City on Saturday.
The Blues ran out 1-0 winners at Etihad Stadium thanks to Raheem Sterling's 23rd-minute strike, with the Gunners ultimately missing the chance to put pressure on Premier League leaders Everton.
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Pep Guardiola won the battle of teacher against pupil as one-time City assistant Arteta failed to mastermind the downfall of his former employers, despite a disciplined performance from the Gunners.