Patrick Vieira does not believe former club Arsenal have the same 'killer attitude' as Premier League leaders Manchester United.
Vieira enjoyed a hugely successful spell with the Gunners from 1996 to 2005 before leaving for Juventus.
After four-and-a-half years in Italy he returned to the Premier League with Manchester City, but still has a lot of affection for Arsenal.
However, there has been a trophy drought at Emirates Stadium since Vieira's departure and he has now questioned what has gone wrong.
The Frenchman feels the lack of a physical element to the Gunners' game may have proved costly in their quest for honours.
He told L'Equipe: "I still have warm feelings for Arsenal, but it's starting to become frustrating.
"They play the best football in England, yet they fail to win anything significant.
"I really enjoy watching them, but they lack the physicality to impose themselves.
"Arsenal don't have the killer attitude that a team like Manchester United have.
"[Tony] Adams, [Martin] Keown, [Nigel] Winterburn and [Ray] Parlour weren't as good with the ball as the current players, but they put their head where others won't even put feet."