PLEASANTON -- A man who was stabbed in the back at a fight behind a bar said he was attacked by another man who was harrassing his girlfriend and that he went home before realizing the severity of his wound.

The 27-year-old Pleasanton resident walked into the emergency room at the ValleyCare Medical Care at 5555 W. Las Positas Boulevard in Pleasanton around 8:11 a.m. Saturday, saying he had been involved in a fight the night before and was stabbed.

He sustained a single non-life threatening stab wound to his back. He was treated and released from the hospital.

The man told police he went to pick up his girlfriend who told him she was being harassed by a male at the bar.

The man arrived at the back of the Red Coats Pub, 336 St. Mary's St., and an altercation ensued between him and the other male.

During the fight, the suspect pulled out a knife and stabbed the victim once in the back, before fleeing the area on foot.

The victim left the scene with his girlfriend believing the wound was not serious. It was not until Saturday morning that he realized he needed medical attention.

A check of calls for service showed that at approximately 12:37 a.m., Pleasanton police received a call of a fight in the parking lot to the rear of the Red Coats Pub.

The caller reported two males fighting and that a female was possibly involved. Officers responded and checked the area at the time, but could not locate any of the involved parties or witnesses. No additional calls were made to the police to report the incident by any of the involved parties.

Anyone with information can contact Pleasanton police at 925-931-5100.

Contact Katie Nelson at 925-945-4780 or follow her at Twitter.com/katienelson210.