Justin Bieber gave an injured fan the "best day of her life" after playing a private gig for her.

The Canadian performed an intimate show today (December 4) in Melbourne for 19-year-old Kate O'Neill, who was recently hospitalised after a car crash.

Her injuries made her unable to attend any of her idol's Australian tour dates and a campaign soon began for the singer to visit her in hospital.

However, Bieber went one further by taking O'Neill to a private studio location, where he performed a number of acoustic songs for her and around 50 friends and fans.

The singer tweeted after the show: "That was fun and all for you Kate. Love u @BieberMelbourne. Stay strong."

O'Neill meanwhile excitedly tweeted: "JUSTIN PUT ON A SECRET PRIVATE SURPRISE ACOUSTIC SHOW AND FOR ME AND MY FRIENDS SINCE I CANT GO TO THE BELIEVE TOUR IT WAS SO PERFECT."

She added: "MY EYES ARE STINGING FROM THE AMOUNT OF TEARS I HAVE CRIED TONIGHT." Watch Justin Bieber live on tour below: