A plucky PATH rider turned the tables on a serial sex fiend who twice rubbed up against her on the train — snapping a cellphone photo that helped cops arrest the creep, sources said.

The 28-year-old Jersey City victim grew tired of the alleged antics of Gian Verdelli, 61, a registered sex offender who has a record of 168 arrests since 1970.

He allegedly attacked her on June 30 and July 3 aboard trains headed for West 33rd Street, the sources said.

On July 6, she spotted the same bearded man — and this time, she took out her cellphone and snapped his picture. Police arrested him on Monday.