The Gunners currently lie fifth in the Premier League table, five points behind north London rivals Tottenham who occupy the final Champions League qualification position.
But, with Arsenal having posted three wins in their last four league games, Diaby insists they can can clinch a top four spot if they stay calm and play their natural game.
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"It is really intense because there are more than four teams [going for it] - there are maybe six teams who could be in the top four. It will be a big fight and I think it will go to the end of the season.
"It is really important to stay calm because we know that when you are nervous you don't produce something good. When you’re calm you can produce something really efficient, so we must work in serenity and play our game."
The France international also pointed to last season's late run of good form as a reason to believe that a surge up the table is possible.
"Last year people did not expect us to be in the top four and in the end we finished third. We need to come with the same mentality this year and prove our potential,” he said.
"I still think we could finish second because we are only nine points off, but we are really far off first so that will be very hard. But we just need to play, enjoy our game and keep winning and everything will be okay."