Unexpected visitor causes concern for Hannigan.

Alyson Hannigan loves meeting her audience, but one over-enthusiastic fan discovered that it's always best to make an appointment after an incident at the weekend.

According to the Mirror newspaper, an intruder slipped backstage after a performance of Alyson's play, When Harry Met Sally, and tried to get into her dressing room over the weekend.

The 'fan' bypassed security, only to discover that Alyson wasn't actually in there.

An insider told the newspaper: "This guy in his mid-20s was hanging around the stage door after the performance. He tried to sneak into Alyson's room but was stopped by security. There was a lot of shouting and swearing and neither Alyson or [co-star] Luke (Perry) were allowed to leave until he had been ushered out of the way."

A spokesman for the theatre attempted to play down the incident, saying: "Somehow an audience member found himself backstage after going through the wrong exit door.

"He took a wrong turn and found himself at her dressing room and thought he'd go in and try and grab her autograph.

"It was dealt with quickly and he was asked to leave."