Roberto Di Matteo’s Chelsea host the Champions League holders at Stamford Bridge on Wednesday night, before the return leg at Camp Nou next Tuesday.
But Djourou insists Arsenal, who suffered a shock 2-1 defeat by Wigan Athletic in north London on Monday night, must be prepared for a battle with a Chelsea side still harbouring hopes of a top-four finish.
“They still want to have Champions League football next season as well so we know it is going to be a tough game,” Djourou told Arsenal Player.
“Obviously they have a lot of fixtures, the two Barcelona games are [either side of Saturday’s derby] but we don’t really concentrate on that. We have to be focused on our game and be focused on what we do best.
“We need to play football the way we did against Manchester City and Wolves, that is the sort of situation we have to get back into. We have to show that again. Unfortunately it wasn’t the case against Wigan but we have to be sure it is there on Saturday.”
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news