A port authority official took the picture of Abdul Basher reclining in his chair at 2:45 a.m. Saturday.
But, the 65-year-old guard denies he was sleeping on the job.
Basher tells the NY Post he was "exercising his eyes" because of a nerve condition.
The firing comes after the arrest of three people accused of parachuting from the World Trade Center and the arrest of a 16-year-old accused of climbing to the top of the nation's biggest skyscraper.