Diaby out until end of August
"Abou had ankle surgery during the close-season break," manager Arsene Wenger told the club's website on Friday.
"He should be back eight to 10 weeks after his surgery which means the end of August."
Diaby was hampered by his ankle problem last term and has not featured for Arsenal in pre-season, missing the tour of Asia and the club's training camp in Germany.
He is certain to miss next month's Premier League games against Newcastle United, Liverpool and Manchester United plus the Champions League playoff against as yet unknown opposition.