Liverpool fought back with a header from Sami Hyypia on the half hour.
The strike partnership of Fernando Torres and Peter Crouch also failed to click at first and it was not until Steven Gerrard moved into a more familiar central position after 25 minutes that Liverpool began to come back into the game.
Liverpool equalised after 30 minutes when Arsenal left Hyypia unmarked at a Gerrard corner and the tall Finnish defender powered a header inside the far post.
Complete Coverage: UEFA Champions League