Tony Adams thinks Arsenal were wrong to sell striker Robin van Persie to Manchester United and fears the Gunners will have another trophyless season.
Without silverware since 2005, for £24m.
"I thought Robin was a mistake," former Arsenal skipper Adams told BBC Sport. "I think he could have played for four or five more years.
"I hope they do go on and win everything. Realistically, I think they will fall short again."
Manager Arsene Wenger, whose last trophy was the FA Cup in 2005, may find it hard to do without his top scorer from last season.
Van Persie registered 44 goals in 57 games for club and country before moving to Old Trafford in the summer.
The Netherlands international still had a year left on his contract but insisted he had a new deal.
"I wouldn't have made that decision [to sell Van Persie]," said Adams in an interview with Saturday's edition of Football Focus.
"Because I do believe if you want to win major trophies you need [the] best players."
Adams also suggested his former centre-back partner Steve Bould may struggle in his as Arsenal's assistant manager.
The concession of seven goals in nine matches this season contrasts to 17 at the same point last year, and Bould has received widespread credit for the defensive improvement.
But each of the last five goals they have let in have come from crosses or set-pieces.
"It's a blessing and a curse for Steve," said Adams, who scored 48 goals in 669 appearances for Arsenal during a career lasting 18 years.
"People are going to say 'what a fantastic defence' because he played defence. And a goal goes in they're all going to be turning round to him and saying 'come on Steve you're doing a really bad job'.
"My experience of Arsene Wenger is that he's very offensive and it's going to be very difficult for Steve."