Don't mess with his sister.

Actor Colin Farrell -- no stranger to grabbing headlines at the Toronto International Film Festival -- grabbed an unnamed photographer by the scruff of his neck to teach a quick lesson in manners at the Winter Garden Theatre last night after the media hordes yelled at his sister Claudine Farrell to get out of the way.

iPhoto photographer Jorge Rios witnessed the dust-up and told the Sun several photogs loudly -- and impolitely -- asked Farrell's sister to "get off the carpet" to make way for her famous brother at the premiere of his new movie Triage.

Few in the crowd knew they were yelling at Farrell's flesh and blood.

Like a knight in shining armour, when the leading man heard one photographer shouting the loudest at his kin, he jumped to her aid in a chivalrous display that is sure to raise the sexy star's stock among adoring female fans.

"Don't yell at her," Rios and other photographers heard Farrell tell the shooter. "That's my sister you're yelling at.

"You shouldn't yell at any woman like that."

The now-subdued shutterbugs caught the Hollywood star on camera approaching the loudmouthed photographer with his finger pointed and as he pulled the man closer to speak in his sister's defence.

The photographer quickly and repeatedly could be heard apologizing to the star.

Farrell has made news off-screen at TIFF before.

In 2007 the star befriended a beggar named "Stress" and helped him get clean, sober and off the streets.

A year later, the Sun's Mike Strobel reported Stress' firm belief that, "Colin Farrell saved (his) life."

It was the second day in a row an uncomfortable incident marred the festivities. Friday, actress Jennifer Connellyw broke down in tears after an industry honcho ridiculed her for cutting short an appearance when she left an event early because she was grieving her dead father.