However, Gallas, 31, has been honest enough to hold his hands up to the lapse in concentration - but has vowed it is not going to become a regular habit.
"I did not defend very well for the Fulham goal, I am not afraid to admit that," said the Arsenal captain, who was on target himself in the 4-0 Champions League qualifying win over FC Twente on Wednesday night.
"It was my player and I did not do well enough - I made a mistake and I know I have to be close to my player next time.
"It is sometimes good to play every three days because you get the chance to put the last game behind you."