Arsene Wenger admits Arsenal's Barclays Premier League title aspirations are over following their 2-1 defeat at Tottenham.
The Gunners were beaten by their north London rivals for the first time in the league in 11 years with a wonder-strike from Danny Rose and second-half goal by Gareth Bale sealing the outcome.
The six-point gap between Arsenal and leaders Chelsea still stands and, with just four matches remaining, Wenger concedes his side are out of the running.
"We lost a game we couldn't afford to lose in the title race," said the Gunners boss.
"That shows that we're not mature enough because you can't afford to lose this type of game if you want to win the championship.
"There's too much to do now. We're very unlikely now to win the championship.
"We'll continue to fight but even a point wasn't enough against Tottenham - we needed three points."
Arsenal also lost defender Thomas Vermaelen for two to three weeks with a calf injury but took some consolation from the superb second half substitute appearance of Robin van Persie.
Harry Redknapp felt Tottenham's response to Sunday's FA Cup semi-final defeat by Portsmouth proved their character.
Spurs are now right back in the race for the final Champions League spot, trailing fourth place Manchester City by one point.
"It was a real London derby, very competitive and played in a good spirit," said Redknapp.
"We worked very hard and lifted ourselves after a difficult day on Sunday. To come out and turn in a performance like that was great.
"Arsenal were the perfect game for us to play, the crowd were passionate and got behind us.
"We knew the importance of the game and that if we won we still have a big chance of fourth. The players responded with a fabulous performance.
"We're still in there for fourth but it's going to be hard."
Redknapp praised Rose's wonder-strike with the 19-year-old, making his league debut, viciously volleying Manuel Almunia's punched clearance home.
"It was an amazing goal from Danny. He's a left sided player but I played him on the right because I thought he'd give us a bit of energy," he said.
"That was a wonderful strike and we'll never forget that."Reuse content