Cesc blames mental fatigue for his lapse.
"It was a mental block," he told the club's official website. "Tito has made it clear that I need to play the way I know. I have to be mobile and look for space, help my team-mates by playing the easy ball.
"I've noticed the difference in the first few games of pre-season - how rather than staying static on the inside left, I have to be more mobile.
"These three weeks of pre-season help to make us stronger and we need to fuel ourselves in order to perform better during the season. A good pre-season builds fitness to see you through until the end."