Third-placed Spurs - inspired by Gareth Bale in recent weeks - will open up a seven-point lead over their neighbours with a repeat of last season's victory in the equivalent fixture.
In the meantime, though, Arsenal have twice run out 5-2 winners on derby day - most recently in November after Spurs had Emmanuel Adebayor sent off while leading 1-0.
And Diaby, who could miss the game with a calf injury, told his club's official website: "Of course (we have a psychological edge) because from the last game against them we took some lessons and we know them well. We know how to deal with them.
"We all look forward to these big games because they are not only important to us, but to the club and the fans. It is more than a game.
"The atmosphere around the game means we all want to win, so that makes it very exciting. That is why I think there are so many goals.
"It will be difficult because they play at their ground and have the crowd supporting them. But we just have to deal with that."