Arsenal goalkeeper Petr Cech said Arsenal had taken "a step back" with their 3-2 defeat at Manchester United on Sunday.
But Cech stressed that they could recover lost ground by winning two Premier League matches next week.
The defeat to United leaves the Gunners five points behind leaders Leicester and three behind Tottenham ahead of a huge North London derby at White Hart Lane next weekend.
Before that, they face Swansea on Wednesday, and Cech told Arsenal's official website: "We still have a chance, so we will go for it until the last minute.
"This was a big disappointment for us and is a step back after last week, where we managed to overcome a deficit against Leicester at home.
"It's a step back but we can still make up for this. We have two important games coming up this week and, if we manage to win both, the table might look better again."
Arsenal have not won at Old Trafford in the league since 2006, but were the favourites against an injury-hit United team outside the top four.
But 18-year-old Marcus Rashford scored twice and set up the third for Ander Herrera.
Cech said he had not been surprised by United's strong performance, adding: "Man United away is a big game.
"They are fighting to have a chance to enter the top four, so we knew it was going to be a difficult game. In a game like this, you can make mistakes, and we were punished for them.
"At 3-1 down you try to get one back as soon as possible, which we managed to do. But we didn't create enough to score in the last 10 minutes."