The 'Believe' hitmaker got into an altercation with Melinda Giel-Murray at Circle K Stables in Burbank, California on Monday (12.05.14), just hours before he allegedly tried to take a woman's phone at a mini-golf course.
Melinda told TMZ she was at the stables with her horse when the 20-year-old star arrived to go riding, and as soon as she pulled out her camera, Justin freaked out.
In video footage, he can be heard pointing out Melinda and saying: "...that b***h over there".
The rider went on to say four of the star's security guards surrounded her and tried to "intimidate" her, but she stood her ground and told them there was no law against her taking photographs.
The 'Beauty and a Beat' hitmaker - who she described as acting "very strange and nervous" - then drove to another part of the stable to mount up, which he did without a shirt on.
It was revealed earlier this week that police are investigating claims the Canadian star tried to steal a woman's phone at Sherman Oaks Castle Park.
The unnamed woman claimed Justin demanded to see her phone so he could delete the pictures however when she refused he grabbed it from her bag.
She began "wrestling" with the star for the phone, and although he "ripped it out of her hands" he wasn't able to access the pictures because the phone was locked.
Justin then demanded she unlock it and she proved she hadn't taken any snaps.
The singer has not yet been questioned by police over the alleged incident, but later took to twitter to apparently deny the claims.