Unai Emery has warned Arsenal that losing to bitter rivals Chelsea on Saturday would end their hopes of finishing in the Premier League's top four.
Emery's side host Chelsea in a crucial clash at the Emirates Stadium knowing a defeat would leave them nine points adrift of the Champions League places.
After a 22-game unbeaten run earlier this season, Arsenal struggled over the festive period and lost at West Ham last weekend.
Emery's men could kick off in sixth place if Manchester United get a positive result against Brighton earlier in the day.
The fact United were 12 points behind Arsenal when Jose Mourinho was sacked in mid-December shows how much the north Londoners' form has slipped of late.
And Emery feels another defeat to Chelsea, following on from a 3-2 reverse at Stamford Bridge on the second weekend of the season, would spell the end of any hopes of a first top-four finish in three years.
Asked if a nine-point gap would be too big to overturn, the Arsenal head coach replied: "I think yes.
"We had a big challenge against West Ham. And the reason is because we spoke about playing under pressure, which we have to do if we are to be competitive, and take this opportunity. It is a big ambition of ours to do that.
"After our loss to West Ham it is a big difference to be six points behind Chelsea instead of three points behind.
"But the next match is against Chelsea and the opportunity we have is not the same, but if we win we have the opportunity to be closer to them.
"And we can then continue our way in the 38 matches in the Premier League. Every player has this ambition. To play Saturday with all we can against them."