Chris Brown's girlfriend is sticking by him as he heads to rehab.

Karrueche Tran is standing by her man after a judge sentenced the R&B star to ninety days in a live-in rehabilitation centre to focus on his anger issues.

According to Hollywoodlife.com, Karrueche was with her boyfriend after the court case and gave him words of support.

The source said: ''They were together afterwards and she held his hand when they walked out, and in the car ride home, he laid his head on her shoulder.

''She thought he wanted to cry but Chris will never let anyone see him like that.''

She supposedly told Chris to ''keep his head up'' and focus on getting better in rehab.

Karrueche, 25, was by Chris' side when he left Los Angeles County Superior Court, and she tried to cheer him up after his daunting new rehab sentence.

The 24-year-old was believed to be putting on a brave front as he's still ''terrified'' he could be sent to prison.

The source added: ''Karrueche told him, 'Keep your head up and stop thinking about what everyone else is saying.

''Focus and get all this sh*t done so you can put it all behind you. Don't worry, I'm here,' She was hoping that would lift him up.''

The judge is cracking down on the case after Chris was reportedly kicked out of rehab for throwing a rock at his own mother's car window when she visited him for a 'family session'.

He was sentenced during a probation status hearing stemming from his 2009 assault on then-girlfriend, pop star Rihanna.