Arsenal club legend Robert Pires believes that Mesut Ozil will have been angered by Arsene Wenger's reluctance to spend big in the transfer market.
Ozil is approaching the final six months of his deal at Arsenal, with Wenger acknowledging that the Germany international - along with fellow contract rebel Alexis Sanchez - may well be sold in the January transfer window.
And Pires, a stalwart of Arsenal's most successful period under Wenger's tutelage, claims Ozil has been frustrated by Arsenal's failure to add further stars to their squad.
"Ozil is a warrior who wants to win something," Pires told German publication Bild.
"To me, he seems so angry about the fact that Arsenal haven't put together the team with which he can make a difference.
"Arsenal has spent money only for Alexander Lacazette. That is not enough to be at the top."
Arsenal sit sixth in the Premier League, having suffered their third defeat of the season when they slumped to a 2-1 reverse against Watford on Saturday.
The pressure is on Wenger to deliver - at the least - a return to the Champions League next season with a top four finish, but Pires has no doubts that his former boss is still the right man to take charge at Emirates Stadium.
"It's incredibly difficult to consistently remain at the top in England," the Frenchman added.
"But I still believe in Arsenal and first of all in Arsene Wenger. I think it's right he penned a new two-year deal."