The Arsenal board are reportedly furious that the club let Ismael Bennacer leave the Gunners in 2017, with the French midfielder now tearing up Serie A with AC Milan.
Bennacer spent two years in north London under Arsene Wenger, making just one appearance before joining Italian second division side Empoli.
The Frenchman helped his new side to promotion straight away in his first season there but at the end of the following season AC Milan placed a £14million bid.
And according to Calciomercato, Arsenal had the option to match Milan's bid via a clause in Bennacer's contract but the Premier League club - then managed by Unai Emery - turned down the opportunity as the offer was too large.