A campaign on Twitter convinced pop sensation Justin Bieber to pay a visit to an Edmonton teenager who is fighting bone cancer.

Bieber visited 18-year-old Crystal Montgomery at the Cross Cancer Clinic hours before his sold-out concert at Rexall Place.

The pop star subsequently tweeted an Instagram photo of himself with the young woman, using #bieberforcrystal, the hashtag created by her friends for their campaign.

Bieber, 18, has been seen at a number of spots in Edmonton, including the Blue Plate Diner, since Saturday.