Alexis Sanchez believes Arsenal "lack self-belief" to become Premier League champions this season.
The Gunners blew a big chance to increase the pressure on leaders Leicester when they were beaten at home 2-1 by Swansea on Wednesday night.
Joel Campbell had opened the scoring for Arsenal, who also hit the woodwork on three occasions, but goals from Wayne Routledge and Ashley Williams saw Swansea leave the Emirates Stadium with all three points for the third time in four years.
It was a much-changed Swans line-up, showing six alterations from the weekend defeat to Tottenham and with more than an eye on a crunch match at home to fellow strugglers Norwich on Saturday.
They picked up the win without head coach Francesco Guidolin, who was admitted to a London hospital with a chest infection, but still managed to dent both Arsenal's confidence and their title hopes.
And Sanchez, who hit the post in the first half before cracking a second-half free-kick against the crossbar, feels it is the confidence of the squad that has seen them embark on a damaging run of just three wins from 11 games in all competitions.
"We lack self-belief, that we can actually be champions," he said ahead of tomorrow's crunch North London derby clash with Tottenham at White Hart Lane.
"I think we can win the Premier League with the players we have. That said, we lack a certain hunger. We need to step out onto the pitch as if we're already 1-0 up.
"I remember a game against Manchester United last year. The lads looked hungry for silverware as we took to the pitch.
"We crushed them in the first 20 minutes and went 3-0 up. We were hungry and brimming with confidence that day."
Meanwhile, former Tottenham and Arsenal goalkeeper Pat Jennings has warned against the north London rivals placing too much emphasis on their derby clash tomorrow as they continue to battle for the Premier League title.
The lunchtime kick-off at White Hart Lane has been touted as one of the biggest-ever meetings between Spurs and the Gunners, who are currently second and third in the table respectively behind surprise leaders Leicester.
Jennings has no doubt it is a "massive" fixture, but has also emphasised any winner of it will still have plenty of work ahead of them in this thoroughly unpredictable season.
The 70-year-old former Northern Ireland international said: "Tottenham-Arsenal matches have always been massive, so nothing had changed there - it is just the fact it could be a step towards winning the Premier League this time.
"But it is so important you win every game. Take each one as it comes. Even if you are to win on Saturday, that doesn't guarantee anything.
"You have to keep it going."
As Jennings acknowledges, even then, the current table-toppers could still prove uncatchable.
"There are still a lot of games to be played and anything can happen. Leicester could still be there at the end of the day," he added.